diff --git a/addons/hr_holidays/static/tests/leave_stats_tests.js b/addons/hr_holidays/static/tests/leave_stats_tests.js
index a49918be2e4..b1684184674 100644
--- a/addons/hr_holidays/static/tests/leave_stats_tests.js
+++ b/addons/hr_holidays/static/tests/leave_stats_tests.js
@@ -154,10 +154,10 @@ QUnit.test("leave stats reload when employee/department changes", async (assert)
             </form>`,
         mockRPC(route, args) {
             if (args.model === "hr.leave" && args.method === "search_read") {
-                assert.ok(_.some(args.kwargs.domain, _.matcher(["department_id", "=", 11])));
+                assert.ok(args.kwargs.domain.some(_.matcher(["department_id", "=", 11])));
             }
             if (args.model === "hr.leave" && args.method === "read_group") {
-                assert.ok(_.some(args.kwargs.domain, _.matcher(["employee_id", "=", 200])));
+                assert.ok(args.kwargs.domain.some(_.matcher(["employee_id", "=", 200])));
             }
         },
     });
diff --git a/addons/im_livechat/static/src/legacy/public_models/livechat_button_view.js b/addons/im_livechat/static/src/legacy/public_models/livechat_button_view.js
index 18d844e0a44..7ea79b5a56e 100644
--- a/addons/im_livechat/static/src/legacy/public_models/livechat_button_view.js
+++ b/addons/im_livechat/static/src/legacy/public_models/livechat_button_view.js
@@ -22,11 +22,8 @@ Model({
          * @param {Object} [options={}]
          */
         addMessage(data, options) {
-            const hasAlreadyMessage = _.some(
-                this.messaging.publicLivechatGlobal.messages,
-                function (msg) {
-                    return data.id === msg.id;
-                }
+            const hasAlreadyMessage = this.messaging.publicLivechatGlobal.messages.some(
+                (msg) => data.id === msg.id
             );
             if (hasAlreadyMessage) {
                 return;
diff --git a/addons/mass_mailing/static/src/js/snippets.editor.js b/addons/mass_mailing/static/src/js/snippets.editor.js
index 13ed75c22fe..6b0001bc143 100644
--- a/addons/mass_mailing/static/src/js/snippets.editor.js
+++ b/addons/mass_mailing/static/src/js/snippets.editor.js
@@ -4,16 +4,16 @@ import {_lt} from "web.core";
 import snippetsEditor from "web_editor.snippet.editor";
 
 const MassMailingSnippetsMenu = snippetsEditor.SnippetsMenu.extend({
-    events: _.extend({}, snippetsEditor.SnippetsMenu.prototype.events, {
+    events: Object.assign({}, snippetsEditor.SnippetsMenu.prototype.events, {
         'click .o_we_customize_design_btn': '_onDesignTabClick',
     }),
-    custom_events: _.extend({}, snippetsEditor.SnippetsMenu.prototype.custom_events, {
+    custom_events: Object.assign({}, snippetsEditor.SnippetsMenu.prototype.custom_events, {
         drop_zone_over: '_onDropZoneOver',
         drop_zone_out: '_onDropZoneOut',
         drop_zone_start: '_onDropZoneStart',
         drop_zone_stop: '_onDropZoneStop',
     }),
-    tabs: _.extend({}, snippetsEditor.SnippetsMenu.prototype.tabs, {
+    tabs: Object.assign({}, snippetsEditor.SnippetsMenu.prototype.tabs, {
         DESIGN: 'design',
     }),
     optionsTabStructure: [
diff --git a/addons/point_of_sale/static/src/js/db.js b/addons/point_of_sale/static/src/js/db.js
index 849f2229755..43b069bf974 100644
--- a/addons/point_of_sale/static/src/js/db.js
+++ b/addons/point_of_sale/static/src/js/db.js
@@ -231,7 +231,7 @@ export const PosDB = core.Class.extend({
     add_packagings: function (product_packagings) {
         var self = this;
         _.map(product_packagings, function (product_packaging) {
-            if (_.find(self.product_by_id, { id: product_packaging.product_id[0] })) {
+            if (self.product_by_id.find(({ id }) => id === product_packaging.product_id[0])) {
                 self.product_packaging_by_barcode[product_packaging.barcode] = product_packaging;
             }
         });
diff --git a/addons/point_of_sale/static/src/js/models.js b/addons/point_of_sale/static/src/js/models.js
index ad37eca3349..fafb60f846b 100644
--- a/addons/point_of_sale/static/src/js/models.js
+++ b/addons/point_of_sale/static/src/js/models.js
@@ -1679,7 +1679,7 @@ export class Product extends PosModel {
         let price_extra = 0.0;
         let draftPackLotLines, weight, description, packLotLinesToEdit;
 
-        if (_.some(this.attribute_line_ids, (id) => id in this.pos.attributes_by_ptal_id)) {
+        if (this.attribute_line_ids.some((id) => id in this.pos.attributes_by_ptal_id)) {
             const attributes = _.map(
                 this.attribute_line_ids,
                 (id) => this.pos.attributes_by_ptal_id[id]
@@ -1769,8 +1769,9 @@ export class Product extends PosModel {
         return { draftPackLotLines, quantity: weight, description, price_extra };
     }
     isPricelistItemUsable(item, date) {
+        const categories = this.parent_category_ids.concat(this.categ.id);
         return (
-            (!item.categ_id || _.contains(this.parent_category_ids.concat(this.categ.id), item.categ_id[0])) &&
+            (!item.categ_id || categories.includes(item.categ_id[0])) &&
             (!item.date_start || moment.utc(item.date_start).isSameOrBefore(date)) &&
             (!item.date_end || moment.utc(item.date_end).isSameOrAfter(date))
         );
@@ -1824,13 +1825,13 @@ export class Product extends PosModel {
         if (price_extra) {
             price += price_extra;
         }
-        _.find(pricelist_items, function (rule) {
+        pricelist_items.find(function (rule) {
             if (rule.min_quantity && quantity < rule.min_quantity) {
                 return false;
             }
 
             if (rule.base === "pricelist") {
-                const base_pricelist = _.find(self.pos.pricelists, function (pricelist) {
+                const base_pricelist = self.pos.pricelists.find(function (pricelist) {
                     return pricelist.id === rule.base_pricelist_id[0];
                 });
                 if (base_pricelist) {
@@ -1949,10 +1950,7 @@ export class Orderline extends PosModel {
         var pack_lot_lines = json.pack_lot_ids;
         for (var i = 0; i < pack_lot_lines.length; i++) {
             var packlotline = pack_lot_lines[i][2];
-            var pack_lot_line = new Packlotline(
-                {},
-                { json: _.extend({ ...packlotline }, { order_line: this }) }
-            );
+            var pack_lot_line = new Packlotline({}, { json: { ...packlotline, order_line: this } });
             this.pack_lot_lines.add(pack_lot_line);
         }
         this.tax_ids = json.tax_ids && json.tax_ids.length !== 0 ? json.tax_ids[0][2] : undefined;
@@ -2335,8 +2333,8 @@ export class Orderline extends PosModel {
             tax: this.get_tax(),
             product_description: this.get_product().description,
             product_description_sale: this.get_product().description_sale,
-            pack_lot_lines:      this.get_lot_lines(),
-            customer_note:      this.get_customer_note(),
+            pack_lot_lines: this.get_lot_lines(),
+            customer_note: this.get_customer_note(),
             taxed_lst_unit_price: this.get_taxed_lst_unit_price(),
         };
     }
@@ -2425,26 +2423,27 @@ export class Orderline extends PosModel {
             return this.get_base_price();
         }
     }
-    get_taxed_lst_unit_price(){
+    get_taxed_lst_unit_price() {
         var lst_price = this.compute_fixed_price(this.get_lst_price());
-        if (this.pos.config.iface_tax_included === 'total') {
-            var product =  this.get_product();
+        if (this.pos.config.iface_tax_included === "total") {
+            var product = this.get_product();
             var taxes_ids = product.taxes_id;
             var product_taxes = this.pos.get_taxes_after_fp(taxes_ids);
-            return this.compute_all(product_taxes, lst_price, 1, this.pos.currency.rounding).total_included;
+            return this.compute_all(product_taxes, lst_price, 1, this.pos.currency.rounding)
+                .total_included;
         }
         return lst_price;
     }
-    get_price_without_tax(){
+    get_price_without_tax() {
         return this.get_all_prices().priceWithoutTax;
     }
-    get_price_with_tax(){
+    get_price_with_tax() {
         return this.get_all_prices().priceWithTax;
     }
-    get_price_with_tax_before_discount () {
+    get_price_with_tax_before_discount() {
         return this.get_all_prices().priceWithTaxBeforeDiscount;
     }
-    get_tax(){
+    get_tax() {
         return this.get_all_prices().tax;
     }
     get_applicable_taxes() {
@@ -2598,8 +2597,8 @@ export class Orderline extends PosModel {
     get_fixed_lst_price() {
         return this.compute_fixed_price(this.get_lst_price());
     }
-    get_lst_price(){
-        return this.product.get_price(this.pos.default_pricelist, 1, 0)
+    get_lst_price() {
+        return this.product.get_price(this.pos.default_pricelist, 1, 0);
     }
     set_lst_price(price) {
         this.order.assert_editable();
@@ -2842,7 +2841,7 @@ export class Order extends PosModel {
             this.uid = this.generate_unique_id();
             this.name = _.str.sprintf(_t("Order %s"), this.uid);
             this.validation_date = undefined;
-            this.fiscal_position = _.find(this.pos.fiscal_positions, function (fp) {
+            this.fiscal_position = this.pos.fiscal_positions.find(function (fp) {
                 return fp.id === self.pos.config.default_fiscal_position_id[0];
             });
         }
@@ -2884,7 +2883,7 @@ export class Order extends PosModel {
         this.firstDraft = false;
 
         if (json.fiscal_position_id) {
-            var fiscal_position = _.find(this.pos.fiscal_positions, function (fp) {
+            var fiscal_position = this.pos.fiscal_positions.find(function (fp) {
                 return fp.id === json.fiscal_position_id;
             });
 
@@ -2896,7 +2895,7 @@ export class Order extends PosModel {
         }
 
         if (json.pricelist_id) {
-            this.pricelist = _.find(this.pos.pricelists, function (pricelist) {
+            this.pricelist = this.pos.pricelists.find(function (pricelist) {
                 return pricelist.id === json.pricelist_id;
             });
         } else {
@@ -3325,7 +3324,7 @@ export class Order extends PosModel {
         this.select_orderline(this.get_last_orderline());
     }
 
-    isFirstDraft(){
+    isFirstDraft() {
         return this.firstDraft;
     }
 
diff --git a/addons/portal/static/src/js/portal_chatter.js b/addons/portal/static/src/js/portal_chatter.js
index 9501afb1b20..26ae58bf524 100644
--- a/addons/portal/static/src/js/portal_chatter.js
+++ b/addons/portal/static/src/js/portal_chatter.js
@@ -181,7 +181,7 @@ var PortalChatter = publicWidget.Widget.extend({
             params: this._messageFetchPrepareParams()
         }).then(function (result) {
             self.result = result;
-            self.options = _.extend(self.options, self.result['options'] || {});
+            self.options = Object.assign(self.options, self.result['options'] || {});
             return result;
         });
     },
diff --git a/addons/portal/static/src/js/portal_composer.js b/addons/portal/static/src/js/portal_composer.js
index 25536cd34ff..8908193cc4f 100644
--- a/addons/portal/static/src/js/portal_composer.js
+++ b/addons/portal/static/src/js/portal_composer.js
@@ -78,7 +78,7 @@ var PortalComposer = publicWidget.Widget.extend({
     _onAttachmentDeleteClick: function (ev) {
         var self = this;
         var attachmentId = $(ev.currentTarget).closest('.o_portal_chatter_attachment').data('id');
-        var accessToken = _.find(this.attachments, {'id': attachmentId}).access_token;
+        var accessToken = this.attachments.find(attachment => attachment.id === attachmentId).access_token;
         ev.preventDefault();
         ev.stopPropagation();
 
diff --git a/addons/portal/static/src/js/portal_signature.js b/addons/portal/static/src/js/portal_signature.js
index 533c2ac6784..695e98d72a7 100644
--- a/addons/portal/static/src/js/portal_signature.js
+++ b/addons/portal/static/src/js/portal_signature.js
@@ -111,7 +111,7 @@ var SignatureForm = publicWidget.Widget.extend({
 
         return this._rpc({
             route: this.callUrl,
-            params: _.extend(this.rpcParams, {
+            params: Object.assign(this.rpcParams, {
                 'name': name,
                 'signature': signature,
             }),
diff --git a/addons/portal_rating/static/src/js/portal_chatter.js b/addons/portal_rating/static/src/js/portal_chatter.js
index 984397f7b4d..56ba6dc8975 100644
--- a/addons/portal_rating/static/src/js/portal_chatter.js
+++ b/addons/portal_rating/static/src/js/portal_chatter.js
@@ -15,7 +15,7 @@ var qweb = core.qweb;
  * Extends Frontend Chatter to handle rating
  */
 PortalChatter.include({
-    events: _.extend({}, PortalChatter.prototype.events, {
+    events: Object.assign({}, PortalChatter.prototype.events, {
         // star based control
         'click .o_website_rating_table_row': '_onClickStarDomain',
         'click .o_website_rating_selection_reset': '_onClickStarDomainReset',
@@ -199,7 +199,7 @@ PortalChatter.include({
             ratingData.publisher_name = rawRating.publisher_id[1];
             ratingData.publisher_avatar = _.str.sprintf('/web/image/res.partner/%s/avatar_128/50x50', ratingData.publisher_id);
         }
-        var commentData = _.extend(this._newPublisherCommentData(messageIndex), ratingData);
+        var commentData = Object.assign(this._newPublisherCommentData(messageIndex), ratingData);
         return commentData;
     },
 
diff --git a/addons/portal_rating/static/src/js/portal_composer.js b/addons/portal_rating/static/src/js/portal_composer.js
index d36a5d814d5..49262cc5bf1 100644
--- a/addons/portal_rating/static/src/js/portal_composer.js
+++ b/addons/portal_rating/static/src/js/portal_composer.js
@@ -13,7 +13,7 @@ var PortalComposer = portalComposer.PortalComposer;
  * Extends Portal Composer to handle rating submission
  */
 PortalComposer.include({
-    events: _.extend({}, PortalComposer.prototype.events, {
+    events: Object.assign({}, PortalComposer.prototype.events, {
         'click .stars i': '_onClickStar',
         'mouseleave .stars': '_onMouseleaveStarBlock',
         'mousemove .stars i': '_onMoveStar',
diff --git a/addons/portal_rating/static/src/js/portal_rating_composer.js b/addons/portal_rating/static/src/js/portal_rating_composer.js
index c3e01e30069..eb8f1b74ba0 100644
--- a/addons/portal_rating/static/src/js/portal_rating_composer.js
+++ b/addons/portal_rating/static/src/js/portal_rating_composer.js
@@ -114,7 +114,7 @@ const RatingPopupComposer = publicWidget.Widget.extend({
         delete data.rating_count;
         delete data.rating_value;
 
-        this.options = _.extend(this.options, data);
+        this.options = Object.assign(this.options, data);
 
         this._reloadRatingPopupComposer();
     }
diff --git a/addons/pos_adyen/static/src/js/payment_adyen.js b/addons/pos_adyen/static/src/js/payment_adyen.js
index e423c5d3681..8eb651511b7 100644
--- a/addons/pos_adyen/static/src/js/payment_adyen.js
+++ b/addons/pos_adyen/static/src/js/payment_adyen.js
@@ -102,7 +102,7 @@ export const PaymentAdyen = PaymentInterface.extend({
         var line = order.selected_paymentline;
         var data = {
             SaleToPOIRequest: {
-                MessageHeader: _.extend(this._adyen_common_message_header(), {
+                MessageHeader: Object.assign(this._adyen_common_message_header(), {
                     MessageCategory: "Payment",
                 }),
                 PaymentRequest: {
@@ -156,7 +156,7 @@ export const PaymentAdyen = PaymentInterface.extend({
         var self = this;
         var config = this.pos.config;
         var previous_service_id = this.most_recent_service_id;
-        var header = _.extend(this._adyen_common_message_header(), {
+        var header = Object.assign(this._adyen_common_message_header(), {
             MessageCategory: "Abort",
         });
 
diff --git a/addons/pos_mercury/static/src/js/PaymentScreen.js b/addons/pos_mercury/static/src/js/PaymentScreen.js
index 2a88d82c7a3..32644c7166a 100644
--- a/addons/pos_mercury/static/src/js/PaymentScreen.js
+++ b/addons/pos_mercury/static/src/js/PaymentScreen.js
@@ -425,7 +425,7 @@ patch(PaymentScreen.prototype, "pos_mercury.PaymentScreen", {
             transaction: def,
         });
 
-        var request_data = _.extend(
+        var request_data = Object.assign(
             {
                 transaction_type: "Credit",
                 transaction_code: "VoidSaleByRecordNo",
diff --git a/addons/pos_mercury/static/src/js/pos_mercury.js b/addons/pos_mercury/static/src/js/pos_mercury.js
index b76285d9166..563c7aff0aa 100644
--- a/addons/pos_mercury/static/src/js/pos_mercury.js
+++ b/addons/pos_mercury/static/src/js/pos_mercury.js
@@ -102,7 +102,7 @@ patch(Payment.prototype, "pos_mercury.Payment", {
         this.set_credit_card_name();
     },
     export_as_JSON() {
-        return _.extend(this._super(...arguments), {
+        return Object.assign(this._super(...arguments), {
             paid: this.paid,
             mercury_card_number: this.mercury_card_number,
             mercury_card_brand: this.mercury_card_brand,
diff --git a/addons/pos_six/static/src/js/payment_six.js b/addons/pos_six/static/src/js/payment_six.js
index 23d4cc3fb50..f9361f9a336 100644
--- a/addons/pos_six/static/src/js/payment_six.js
+++ b/addons/pos_six/static/src/js/payment_six.js
@@ -29,7 +29,7 @@ export const PaymentSix = PaymentInterface.extend({
         this.enable_reversals();
 
         var terminal_ip = this.payment_method.six_terminal_ip;
-        var instanced_payment_method = _.find(this.pos.payment_methods, function (payment_method) {
+        var instanced_payment_method = this.pos.payment_methods.find(function (payment_method) {
             return (
                 payment_method.use_payment_terminal === "six" &&
                 payment_method.six_terminal_ip === terminal_ip &&
diff --git a/addons/sale_product_configurator/static/src/js/product_configurator_modal.js b/addons/sale_product_configurator/static/src/js/product_configurator_modal.js
index d98142a52f1..b5b9c83b7f8 100644
--- a/addons/sale_product_configurator/static/src/js/product_configurator_modal.js
+++ b/addons/sale_product_configurator/static/src/js/product_configurator_modal.js
@@ -7,7 +7,7 @@ import ServicesMixin from 'web.ServicesMixin';
 import VariantMixin from 'sale.VariantMixin';
 
 export const OptionalProductsModal = Dialog.extend(ServicesMixin, VariantMixin, {
-    events:  _.extend({}, Dialog.prototype.events, VariantMixin.events, {
+    events:  Object.assign({}, Dialog.prototype.events, VariantMixin.events, {
         'click a.js_add, a.js_remove': '_onAddOrRemoveOption',
         'click button.js_add_cart_json': 'onClickAddCartJSON',
         'change .in_cart input.js_quantity': '_onChangeQuantity',
@@ -37,7 +37,7 @@ export const OptionalProductsModal = Dialog.extend(ServicesMixin, VariantMixin,
     init: function (parent, params) {
         var self = this;
 
-        var options = _.extend({
+        var options = Object.assign({
             size: 'large',
             buttons: [{
                 text: params.okButtonText,
@@ -85,7 +85,7 @@ export const OptionalProductsModal = Dialog.extend(ServicesMixin, VariantMixin,
             force_dialog: self.forceDialog,
             no_attribute: self.rootProduct.no_variant_attribute_values,
             custom_attribute: self.rootProduct.product_custom_attribute_values,
-            context: _.extend({'quantity': self.rootProduct.quantity}, this.context),
+            context: Object.assign({'quantity': self.rootProduct.quantity}, this.context),
         })
         .then(function (modalContent) {
             if (modalContent) {
diff --git a/addons/web/static/src/legacy/js/core/ajax.js b/addons/web/static/src/legacy/js/core/ajax.js
index 6b1445d5382..99b77843859 100644
--- a/addons/web/static/src/legacy/js/core/ajax.js
+++ b/addons/web/static/src/legacy/js/core/ajax.js
@@ -125,7 +125,7 @@ function _genericJsonRpc (fct_name, params, settings, fct) {
 function jsonRpc(url, fct_name, params, settings) {
     settings = settings || {};
     return _genericJsonRpc(fct_name, params, settings, function(data) {
-        return $.ajax(url, _.extend({}, settings, {
+        return $.ajax(url, Object.assign({}, settings, {
             url: url,
             dataType: 'json',
             type: 'POST',
@@ -275,7 +275,7 @@ var loadAsset = (function () {
         if (cache[xmlId]) {
             return cache[xmlId];
         }
-        context = _.extend({}, session.user_context, context);
+        context = Object.assign({}, session.user_context, context);
         const params = {
             args: [xmlId, {
                 debug: config.isDebug()
@@ -316,7 +316,7 @@ var loadAsset = (function () {
     return load;
 })();
 
-_.extend(ajax, {
+Object.assign(ajax, {
     jsonRpc: jsonRpc,
     rpc: rpc,
     loadAsset: loadAsset,
diff --git a/addons/web/static/src/legacy/js/core/dialog.js b/addons/web/static/src/legacy/js/core/dialog.js
index 9dc8936b63c..9069211348d 100644
--- a/addons/web/static/src/legacy/js/core/dialog.js
+++ b/addons/web/static/src/legacy/js/core/dialog.js
@@ -18,11 +18,11 @@ var _t = core._t;
  **/
 var Dialog = Widget.extend({
     tagName: 'main',
-    custom_events: _.extend({}, Widget.prototype.custom_events, {
+    custom_events: Object.assign({}, Widget.prototype.custom_events, {
         focus_control_button: '_onFocusControlButton',
         close_dialog: '_onCloseDialog',
     }),
-    events: _.extend({}, Widget.prototype.events, {
+    events: Object.assign({}, Widget.prototype.events, {
         'keydown .modal-footer button': '_onFooterButtonKeyDown',
     }),
     /**
@@ -411,7 +411,7 @@ Dialog.alert = function (owner, message, options) {
         close: true,
         click: options && options.confirm_callback,
     }];
-    return new Dialog(owner, _.extend({
+    return new Dialog(owner, Object.assign({
         size: 'medium',
         buttons: buttons,
         $content: $('<main/>', {
@@ -464,7 +464,7 @@ Dialog.confirm = function (owner, message, options) {
             click: makeCallback('cancel_callback'),
         }
     ];
-    return new Dialog(owner, _.extend({
+    return new Dialog(owner, Object.assign({
         size: 'medium',
         buttons: buttons,
         $content: $('<main/>', {
@@ -518,7 +518,7 @@ Dialog.safeConfirm = function (owner, message, options) {
             click: options && options.cancel_callback
         }
     ];
-    var dialog = new Dialog(owner, _.extend({
+    var dialog = new Dialog(owner, Object.assign({
         size: 'medium',
         buttons: buttons,
         $content: $content,
diff --git a/addons/web/static/src/legacy/js/core/dom.js b/addons/web/static/src/legacy/js/core/dom.js
index a4125b3f3b8..ca99b78a345 100644
--- a/addons/web/static/src/legacy/js/core/dom.js
+++ b/addons/web/static/src/legacy/js/core/dom.js
@@ -406,7 +406,7 @@ var dom = {
      * @returns {jQuery}
      */
     renderButton: function (options) {
-        var jQueryParams = _.extend({
+        var jQueryParams = Object.assign({
             type: 'button',
         }, options.attrs || {});
 
diff --git a/addons/web/static/src/legacy/js/core/domain.js b/addons/web/static/src/legacy/js/core/domain.js
index edc920450d1..52c6f3a2300 100644
--- a/addons/web/static/src/legacy/js/core/domain.js
+++ b/addons/web/static/src/legacy/js/core/domain.js
@@ -140,13 +140,9 @@ var Domain = collections.Tree.extend({
         } else { // The domain is a set of [name, operator, value] entitie(s)
             switch (this._data) {
                 case "&":
-                    return _.every(this._children, function (child) {
-                        return child.compute(values);
-                    });
+                    return this._children.every(child => child.compute(values));
                 case "|":
-                    return _.some(this._children, function (child) {
-                        return child.compute(values);
-                    });
+                    return this._children.some(child => child.compute(values));
                 case "!":
                     return !this._children[0].compute(values);
             }
diff --git a/addons/web/static/src/legacy/js/core/local_storage.js b/addons/web/static/src/legacy/js/core/local_storage.js
index 544c8b7f75b..b8030940e9d 100644
--- a/addons/web/static/src/legacy/js/core/local_storage.js
+++ b/addons/web/static/src/legacy/js/core/local_storage.js
@@ -20,7 +20,7 @@ try {
      * it's not up to them to handle these cases.
      */
     storage = (function () {
-        var storage = Object.create(_.extend({
+        var storage = Object.create(Object.assign({
                 getItem: localStorage.getItem.bind(localStorage),
                 setItem: localStorage.setItem.bind(localStorage),
                 removeItem: localStorage.removeItem.bind(localStorage),
diff --git a/addons/web/static/src/legacy/js/core/mixins.js b/addons/web/static/src/legacy/js/core/mixins.js
index 14f861a2baa..df1f1e07af2 100644
--- a/addons/web/static/src/legacy/js/core/mixins.js
+++ b/addons/web/static/src/legacy/js/core/mixins.js
@@ -119,7 +119,7 @@ function OdooEvent(target, name, data) {
     this.target = target;
     this.name = name;
     this.data = Object.create(null);
-    _.extend(this.data, data);
+    Object.assign(this.data, data);
     this.stopped = false;
 }
 
@@ -238,7 +238,7 @@ var Events = Class.extend({
  * @name EventDispatcherMixin
  * @mixin
  */
-var EventDispatcherMixin = _.extend({}, ParentedMixin, {
+var EventDispatcherMixin = Object.assign({}, ParentedMixin, {
     __eventDispatcherMixin: true,
     custom_events: {},
     init: function () {
@@ -358,7 +358,7 @@ var EventDispatcherMixin = _.extend({}, ParentedMixin, {
  * @name PropertiesMixin
  * @mixin
  */
-var PropertiesMixin = _.extend({}, EventDispatcherMixin, {
+var PropertiesMixin = Object.assign({}, EventDispatcherMixin, {
     init: function () {
         EventDispatcherMixin.init.call(this);
         this.__getterSetterInternalMap = {};
diff --git a/addons/web/static/src/legacy/js/core/mvc.js b/addons/web/static/src/legacy/js/core/mvc.js
index b1be3646016..074bae32baa 100644
--- a/addons/web/static/src/legacy/js/core/mvc.js
+++ b/addons/web/static/src/legacy/js/core/mvc.js
@@ -183,7 +183,7 @@ var Factory = Class.extend({
             var renderer = self.getRenderer(parent, state);
             var Controller = self.Controller || self.config.Controller;
             const initialState = model.get(handle);
-            var controllerParams = _.extend({
+            var controllerParams = Object.assign({
                 initialState,
                 handle,
             }, self.controllerParams);
diff --git a/addons/web/static/src/legacy/js/core/py_utils.js b/addons/web/static/src/legacy/js/core/py_utils.js
index 1f4b065717a..5e0339dcc53 100644
--- a/addons/web/static/src/legacy/js/core/py_utils.js
+++ b/addons/web/static/src/legacy/js/core/py_utils.js
@@ -105,7 +105,7 @@ function wrap_context(context) {
 }
 
 function eval_contexts(contexts, evaluation_context) {
-    evaluation_context = _.extend(pycontext(), evaluation_context || {});
+    evaluation_context = Object.assign(pycontext(), evaluation_context || {});
     return _(contexts).reduce(function (result_context, ctx) {
         // __eval_context evaluations can lead to some of `contexts`'s
         // values being null, skip them as well as empty contexts
@@ -123,18 +123,18 @@ function eval_contexts(contexts, evaluation_context) {
         case 'compound_context':
             var eval_context = eval_contexts([ctx.__eval_context]);
             evaluated = eval_contexts(
-                ctx.__contexts, _.extend({}, evaluation_context, eval_context));
+                ctx.__contexts, Object.assign({}, evaluation_context, eval_context));
             break;
         }
         // add newly evaluated context to evaluation context for following
         // siblings
-        _.extend(evaluation_context, evaluated);
-        return _.extend(result_context, evaluated);
+        Object.assign(evaluation_context, evaluated);
+        return Object.assign(result_context, evaluated);
     }, {});
 }
 
 function eval_domains(domains, evaluation_context) {
-    evaluation_context = _.extend(pycontext(), evaluation_context || {});
+    evaluation_context = Object.assign(pycontext(), evaluation_context || {});
     var result_domain = [];
     // Normalize only if the first domain is the array ["|"] or ["!"]
     var need_normalization = (
@@ -187,7 +187,7 @@ function get_normalized_domain(domain_array) {
 }
 
 function eval_groupbys(contexts, evaluation_context) {
-    evaluation_context = _.extend(pycontext(), evaluation_context || {});
+    evaluation_context = Object.assign(pycontext(), evaluation_context || {});
     var result_group = [];
     _(contexts).each(function (ctx) {
         if (_.isString(ctx)) {
@@ -204,7 +204,7 @@ function eval_groupbys(contexts, evaluation_context) {
         case 'compound_context':
             var eval_context = eval_contexts([ctx.__eval_context]);
             evaluated = eval_contexts(
-                ctx.__contexts, _.extend({}, evaluation_context, eval_context));
+                ctx.__contexts, Object.assign({}, evaluation_context, eval_context));
             break;
         }
         group = evaluated.group_by;
@@ -217,7 +217,7 @@ function eval_groupbys(contexts, evaluation_context) {
             throw new Error('Got invalid groupby {{'
                     + JSON.stringify(group) + '}}');
         }
-        _.extend(evaluation_context, evaluated);
+        Object.assign(evaluation_context, evaluated);
     });
     return result_group;
 }
@@ -285,7 +285,7 @@ function pycontext() {
  * @param {Object} [context] evaluation context
  */
 function pyeval(type, object, context) {
-    context = _.extend(pycontext(), context || {});
+    context = Object.assign(pycontext(), context || {});
 
     //noinspection FallthroughInSwitchStatementJS
     switch(type) {
@@ -347,7 +347,7 @@ function eval_domains_and_contexts(source) {
 }
 
 function py_eval(expr, context) {
-    return py.eval(expr, _.extend({}, context || {}, {"true": true, "false": false, "null": null}));
+    return py.eval(expr, Object.assign({}, context || {}, {"true": true, "false": false, "null": null}));
 }
 
 /**
diff --git a/addons/web/static/src/legacy/js/core/qweb.js b/addons/web/static/src/legacy/js/core/qweb.js
index 79c5eae3575..8aa392abee3 100644
--- a/addons/web/static/src/legacy/js/core/qweb.js
+++ b/addons/web/static/src/legacy/js/core/qweb.js
@@ -17,7 +17,7 @@ function QWeb(debug, default_dict, enableTranslation) {
         enableTranslation = true;
     }
     var qweb = new QWeb2.Engine();
-    qweb.default_dict = _.extend({}, default_dict || {}, {
+    qweb.default_dict = Object.assign({}, default_dict || {}, {
         '_' : _,
         'JSON': JSON,
         '_t' : translation._t,
diff --git a/addons/web/static/src/legacy/js/core/rpc.js b/addons/web/static/src/legacy/js/core/rpc.js
index d9ceaf225a9..68fe98369ab 100644
--- a/addons/web/static/src/legacy/js/core/rpc.js
+++ b/addons/web/static/src/legacy/js/core/rpc.js
@@ -46,7 +46,7 @@ const rpc = {
             params.args = options.args || [];
             params.model = options.model;
             params.method = options.method;
-            params.kwargs = _.extend(params.kwargs || {}, options.kwargs);
+            params.kwargs = Object.assign(params.kwargs || {}, options.kwargs);
             params.kwargs.context = options.context || params.context || params.kwargs.context;
         }
 
diff --git a/addons/web/static/src/legacy/js/core/session.js b/addons/web/static/src/legacy/js/core/session.js
index abf9e697302..85f13a8de92 100644
--- a/addons/web/static/src/legacy/js/core/session.js
+++ b/addons/web/static/src/legacy/js/core/session.js
@@ -124,7 +124,7 @@ var Session = core.Class.extend(mixins.EventDispatcherMixin, {
             if (!result.uid) {
                 return Promise.reject();
             }
-            _.extend(self, result);
+            Object.assign(self, result);
         });
     },
     session_logout: function () {
@@ -228,8 +228,8 @@ var Session = core.Class.extend(mixins.EventDispatcherMixin, {
      * @returns {Promise} promise indicating the session is done reloading
      */
     session_reload: function () {
-        var result = _.extend({}, session);
-        _.extend(this, result);
+        var result = Object.assign({}, session);
+        Object.assign(this, result);
         return Promise.resolve();
     },
     /**
@@ -247,17 +247,17 @@ var Session = core.Class.extend(mixins.EventDispatcherMixin, {
     rpc: function (url, params, options) {
         var self = this;
         options = _.clone(options || {});
-        options.headers = _.extend({}, options.headers);
+        options.headers = Object.assign({}, options.headers);
 
         // we add here the user context for ALL queries, mainly to pass
         // the allowed_company_ids key
         if (params && params.kwargs) {
-            params.kwargs.context = _.extend(params.kwargs.context || {}, this.user_context);
+            params.kwargs.context = Object.assign(params.kwargs.context || {}, this.user_context);
         }
 
         // TODO: remove
         if (! _.isString(url)) {
-            _.extend(options, url);
+            Object.assign(options, url);
             url = url.url;
         }
         if (self.use_cors) {
@@ -267,7 +267,7 @@ var Session = core.Class.extend(mixins.EventDispatcherMixin, {
         return ajax.jsonRpc(url, "call", params, options);
     },
     url: function (path, params) {
-        params = _.extend(params || {});
+        params = Object.assign(params || {});
         var qs = $.param(params);
         if (qs.length > 0)
             qs = "?" + qs;
diff --git a/addons/web/static/src/legacy/js/core/session_storage.js b/addons/web/static/src/legacy/js/core/session_storage.js
index 24b04cc8201..4a3179d6863 100644
--- a/addons/web/static/src/legacy/js/core/session_storage.js
+++ b/addons/web/static/src/legacy/js/core/session_storage.js
@@ -20,7 +20,7 @@ try {
      * it's not up to them to handle these cases.
      */
     storage = (function () {
-        var storage = Object.create(_.extend({
+        var storage = Object.create(Object.assign({
                 getItem: sessionStorage.getItem.bind(sessionStorage),
                 setItem: sessionStorage.setItem.bind(sessionStorage),
                 removeItem: sessionStorage.removeItem.bind(sessionStorage),
diff --git a/addons/web/static/src/legacy/js/core/widget.js b/addons/web/static/src/legacy/js/core/widget.js
index ae10ff2e19e..d0249a34c54 100644
--- a/addons/web/static/src/legacy/js/core/widget.js
+++ b/addons/web/static/src/legacy/js/core/widget.js
@@ -364,7 +364,7 @@ var Widget = core.Class.extend(mixins.PropertiesMixin, ServicesMixin, {
      * @return {jQuery}
      */
     _makeDescriptive: function () {
-        var attrs = _.extend({}, this.attributes || {});
+        var attrs = Object.assign({}, this.attributes || {});
         if (this.id) {
             attrs.id = this.id;
         }
diff --git a/addons/web/static/src/legacy/js/fields/abstract_field.js b/addons/web/static/src/legacy/js/fields/abstract_field.js
index 5e5f5a94202..1377e1cee4f 100644
--- a/addons/web/static/src/legacy/js/fields/abstract_field.js
+++ b/addons/web/static/src/legacy/js/fields/abstract_field.js
@@ -432,7 +432,7 @@ var AbstractField = Widget.extend({
         if (!formatType) {
             throw new Error(`Missing format type for '${this.name}' value from the '${this.model}' model`);
         }
-        var options = _.extend({}, this.nodeOptions, { data: this.recordData }, this.formatOptions);
+        var options = Object.assign({}, this.nodeOptions, { data: this.recordData }, this.formatOptions);
         return field_utils.format[formatType](value, this.field, options);
     },
     /**
diff --git a/addons/web/static/src/legacy/js/fields/basic_fields.js b/addons/web/static/src/legacy/js/fields/basic_fields.js
index 19047d52a1c..725323b5ed6 100644
--- a/addons/web/static/src/legacy/js/fields/basic_fields.js
+++ b/addons/web/static/src/legacy/js/fields/basic_fields.js
@@ -60,7 +60,7 @@ var TranslatableFieldMixin = {
 var FieldBoolean = AbstractField.extend({
     className: 'o_field_boolean',
     description: _lt("Checkbox"),
-    events: _.extend({}, AbstractField.prototype.events, {
+    events: Object.assign({}, AbstractField.prototype.events, {
         change: '_onChange',
     }),
     supportedFieldTypes: ['boolean'],
@@ -308,10 +308,10 @@ var DebouncedField = AbstractField.extend({
 });
 
 var InputField = DebouncedField.extend({
-    custom_events: _.extend({}, DebouncedField.prototype.custom_events, {
+    custom_events: Object.assign({}, DebouncedField.prototype.custom_events, {
         field_changed: '_onFieldChanged',
     }),
-    events: _.extend({}, DebouncedField.prototype.events, {
+    events: Object.assign({}, DebouncedField.prototype.events, {
         'input': '_onInput',
         'change': '_onChange',
         'blur' : '_onBlur',
@@ -417,10 +417,10 @@ var InputField = DebouncedField.extend({
         var inputAttrs = { placeholder: this.attrs.placeholder || "" };
         var inputVal;
         if (this.nodeOptions.isPassword) {
-            inputAttrs = _.extend(inputAttrs, { type: 'password', autocomplete: this.attrs.autocomplete || 'new-password' });
+            inputAttrs = Object.assign(inputAttrs, { type: 'password', autocomplete: this.attrs.autocomplete || 'new-password' });
             inputVal = this.value || '';
         } else {
-            inputAttrs = _.extend(inputAttrs, { type: 'text', autocomplete: this.attrs.autocomplete || 'off'});
+            inputAttrs = Object.assign(inputAttrs, { type: 'text', autocomplete: this.attrs.autocomplete || 'off'});
             inputVal = this._formatValue(this.value);
         }
 
@@ -1427,7 +1427,7 @@ var FieldText = InputField.extend(TranslatableFieldMixin, {
 var UrlWidget = InputField.extend({
     description: _lt("URL"),
     className: 'o_field_url',
-    events: _.extend({}, InputField.prototype.events, {
+    events: Object.assign({}, InputField.prototype.events, {
         'click': '_onClick',
     }),
     supportedFieldTypes: ['char'],
@@ -1503,7 +1503,7 @@ var UrlWidget = InputField.extend({
 });
 
 var AbstractFieldBinary = AbstractField.extend({
-    events: _.extend({}, AbstractField.prototype.events, {
+    events: Object.assign({}, AbstractField.prototype.events, {
         'change .o_input_file': 'on_file_change',
         'click .o_select_file_button': function () {
             this.$('.o_input_file').click();
@@ -1627,7 +1627,7 @@ var AbstractFieldBinary = AbstractField.extend({
 var FieldBinaryFile = AbstractFieldBinary.extend({
     description: _lt("File"),
     template: 'FieldBinaryFile',
-    events: _.extend({}, AbstractFieldBinary.prototype.events, {
+    events: Object.assign({}, AbstractFieldBinary.prototype.events, {
         'click': function (event) {
             if (this.mode === 'readonly' && this.value && this.recordData.id) {
                 this.on_save_as(event);
diff --git a/addons/web/static/src/legacy/js/fields/field_utils.js b/addons/web/static/src/legacy/js/fields/field_utils.js
index c4ae46602fb..d7d5598d8f0 100644
--- a/addons/web/static/src/legacy/js/fields/field_utils.js
+++ b/addons/web/static/src/legacy/js/fields/field_utils.js
@@ -360,7 +360,7 @@ function formatMonetary(value, field, options) {
         digits = field.digits || digits;
     }
     var formatted_value = formatFloat(value, field,
-        _.extend({}, options , {digits: digits})
+        Object.assign({}, options , {digits: digits})
     );
 
     if (!currency || options.noSymbol) {
@@ -402,9 +402,7 @@ function formatPercentage(value, field, options) {
  * @param {boolean} [options.escape=false] if true, escapes the formatted value
  */
 function formatSelection(value, field, options) {
-    var val = _.find(field.selection, function (option) {
-        return option[0] === value;
-    });
+    var val = field.selection.find(option => option[0] === value);
     if (!val) {
         return '';
     }
diff --git a/addons/web/static/src/legacy/js/fields/relational_fields.js b/addons/web/static/src/legacy/js/fields/relational_fields.js
index 3563b4d6b2c..bd42c66f7af 100644
--- a/addons/web/static/src/legacy/js/fields/relational_fields.js
+++ b/addons/web/static/src/legacy/js/fields/relational_fields.js
@@ -75,12 +75,12 @@ var FieldMany2One = AbstractField.extend({
     description: _lt("Many2one"),
     supportedFieldTypes: ['many2one'],
     template: 'FieldMany2One',
-    custom_events: _.extend({}, AbstractField.prototype.custom_events, {
+    custom_events: Object.assign({}, AbstractField.prototype.custom_events, {
         'closed_unset': '_onDialogClosedUnset',
         'field_changed': '_onFieldChanged',
         'quick_create': '_onQuickCreate',
     }),
-    events: _.extend({}, AbstractField.prototype.events, {
+    events: Object.assign({}, AbstractField.prototype.events, {
         'click input': '_onInputClick',
         'click': '_onLinkClick',
         'focusout input': '_onInputFocusout',
@@ -421,7 +421,7 @@ var FieldMany2One = AbstractField.extend({
         return {
             resModel: this.field.relation,
             domain: this.record.getDomain({fieldName: this.name}),
-            context: _.extend({}, this.record.getContext(this.recordParams), context || {}),
+            context: Object.assign({}, this.record.getContext(this.recordParams), context || {}),
             dynamicFilters: dynamicFilters || [],
             title: _.str.sprintf((view === 'search' ? _t("Search: %s") : _t("Create: %s")), this.string),
             multiSelect: false,
@@ -973,10 +973,10 @@ var FieldMany2ManyTags = AbstractField.extend({
     tag_template: "FieldMany2ManyTag",
     className: "o_field_many2manytags",
     supportedFieldTypes: ['many2many'],
-    custom_events: _.extend({}, AbstractField.prototype.custom_events, {
+    custom_events: Object.assign({}, AbstractField.prototype.custom_events, {
         field_changed: '_onFieldChanged',
     }),
-    events: _.extend({}, AbstractField.prototype.events, {
+    events: Object.assign({}, AbstractField.prototype.events, {
         'click .o_delete': '_onDeleteTag',
     }),
     relatedFields: {
@@ -1125,7 +1125,7 @@ var FieldMany2ManyTags = AbstractField.extend({
             var options = _getSearchCreatePopupOptions.apply(this, arguments);
             var domain = this.record.getDomain({fieldName: this.name});
             var m2mRecords = [];
-            return _.extend({}, options, {
+            return Object.assign({}, options, {
                 domain: domain.concat(["!", ["id", "in", self.value.res_ids]]),
                 multiSelect: true,
                 onSelected: function (recordIds) {
@@ -1293,7 +1293,7 @@ const ListMany2ManyTagsAvatar = FieldMany2ManyTagsAvatar.extend(M2MAvatarMixin,
 });
 
 var FormFieldMany2ManyTags = FieldMany2ManyTags.extend({
-    events: _.extend({}, FieldMany2ManyTags.prototype.events, {
+    events: Object.assign({}, FieldMany2ManyTags.prototype.events, {
         'click .dropdown-toggle': '_onOpenColorPicker',
         'mousedown .o_colorpicker a': '_onUpdateColor',
         'mousedown .o_colorpicker .o_hide_in_kanban': '_onUpdateColor',
@@ -1413,7 +1413,7 @@ var FieldSelection = AbstractField.extend({
     template: 'web.Legacy.FieldSelection',
     specialData: "_fetchSpecialRelation",
     supportedFieldTypes: ['selection'],
-    events: _.extend({}, AbstractField.prototype.events, {
+    events: Object.assign({}, AbstractField.prototype.events, {
         'change': '_onChange',
     }),
     isQuickEditable: true,
@@ -1532,9 +1532,7 @@ var FieldSelection = AbstractField.extend({
     _onChange: function () {
         var res_id = JSON.parse(this.$el.val());
         if (this.field.type === 'many2one') {
-            var value = _.find(this.values, function (val) {
-                return val[0] === res_id;
-            });
+            var value = this.values.find(val => val[0] === res_id);
             this._setValue({id: res_id, display_name: value[1]});
         } else {
             this._setValue(res_id);
@@ -1549,7 +1547,7 @@ var FieldRadio = FieldSelection.extend({
     tagName: 'div',
     specialData: "_fetchSpecialMany2ones",
     supportedFieldTypes: ['selection', 'many2one'],
-    events: _.extend({}, AbstractField.prototype.events, {
+    events: Object.assign({}, AbstractField.prototype.events, {
         'click input': '_onInputClick',
     }),
     isQuickEditable: true,
diff --git a/addons/web/static/src/legacy/js/public/public_root.js b/addons/web/static/src/legacy/js/public/public_root.js
index b33f03f080f..c0da3596fc8 100644
--- a/addons/web/static/src/legacy/js/public/public_root.js
+++ b/addons/web/static/src/legacy/js/public/public_root.js
@@ -48,11 +48,11 @@ var localeDef = lang !== 'en_US' ? loadJS('/web/webclient/locale/' + lang.replac
  * children and handle them.
  */
 export const PublicRoot = publicWidget.RootWidget.extend({
-    events: _.extend({}, publicWidget.RootWidget.prototype.events || {}, {
+    events: Object.assign({}, publicWidget.RootWidget.prototype.events || {}, {
         'submit .js_website_submit_form': '_onWebsiteFormSubmit',
         'click .js_disable_on_click': '_onDisableOnClick',
     }),
-    custom_events: _.extend({}, publicWidget.RootWidget.prototype.custom_events || {}, {
+    custom_events: Object.assign({}, publicWidget.RootWidget.prototype.custom_events || {}, {
         call_service: '_onCallService',
         context_get: '_onContextGet',
         main_object_request: '_onMainObjectRequest',
@@ -124,7 +124,7 @@ export const PublicRoot = publicWidget.RootWidget.extend({
      * @returns {Object}
      */
     _getContext: function (context) {
-        return _.extend({
+        return Object.assign({
             'lang': getLang(),
         }, context || {});
     },
@@ -237,7 +237,7 @@ export const PublicRoot = publicWidget.RootWidget.extend({
      */
     _onCallService: function (ev) {
         function _computeContext(context, noContextKeys) {
-            context = _.extend({}, this._getContext(), context);
+            context = Object.assign({}, this._getContext(), context);
             if (noContextKeys) {
                 context = _.omit(context, noContextKeys);
             }
diff --git a/addons/web/static/src/legacy/js/views/abstract_model.js b/addons/web/static/src/legacy/js/views/abstract_model.js
index 217d2e3c330..439829eb85f 100644
--- a/addons/web/static/src/legacy/js/views/abstract_model.js
+++ b/addons/web/static/src/legacy/js/views/abstract_model.js
@@ -104,9 +104,7 @@ var AbstractModel = mvc.Model.extend({
             value = fieldUtils.parse[field.type](value, field, {isUTC: true});
         } else if (field.type === 'selection' && value === false) {
             // process selection: convert false to 0, if 0 is a valid key
-            var hasKey0 = _.find(field.selection, function (option) {
-                return option[0] === 0;
-            });
+            var hasKey0 = field.selection.find(option => option[0] === 0);
             value = hasKey0 ? 0 : value;
         }
         return value;
diff --git a/addons/web/static/src/legacy/js/views/basic/basic_model.js b/addons/web/static/src/legacy/js/views/basic/basic_model.js
index b3e90f62bce..3057bae513a 100644
--- a/addons/web/static/src/legacy/js/views/basic/basic_model.js
+++ b/addons/web/static/src/legacy/js/views/basic/basic_model.js
@@ -187,7 +187,7 @@ var BasicModel = AbstractModel.extend({
     addDefaultRecord: function (listID, options) {
         var self = this;
         var list = this.localData[listID];
-        var context = _.extend({}, this._getDefaultContext(list), this._getContext(list));
+        var context = Object.assign({}, this._getDefaultContext(list), this._getContext(list));
 
         var position = (options && options.position) || 'top';
         var params = {
@@ -225,7 +225,7 @@ var BasicModel = AbstractModel.extend({
      */
     addFieldsInfo: async function (dataPointID, viewInfo) {
         var dataPoint = this.localData[dataPointID];
-        dataPoint.fields = _.extend({}, dataPoint.fields, viewInfo.fields);
+        dataPoint.fields = Object.assign({}, dataPoint.fields, viewInfo.fields);
         // complete the given fieldInfo with the fields of the main view, so
         // that those field will be reloaded if a reload is triggered by the
         // secondary view
@@ -254,7 +254,7 @@ var BasicModel = AbstractModel.extend({
                 });
             } else {
                 // case 'record': on datapoints of all x2many fields
-                const values = _.extend({}, dataPoint.data, dataPoint._changes);
+                const values = Object.assign({}, dataPoint.data, dataPoint._changes);
                 Object.keys(fieldInfo).forEach(fieldName => {
                     const fieldType = dataPoint.fields[fieldName].type;
                     if (fieldType === 'one2many' || fieldType === 'many2many') {
@@ -335,7 +335,7 @@ var BasicModel = AbstractModel.extend({
                     return false;
                 }
                 // 2.2. no drop on new addition on "UPDATE"
-                var lastEntry = _.last(parent._savePoint);
+                var lastEntry = parent._savePoint.at(-1);
                 if (lastEntry.operation === 'UPDATE' && lastEntry.id === id) {
                     return false;
                 }
@@ -360,7 +360,7 @@ var BasicModel = AbstractModel.extend({
     deleteRecords: function (recordIds, modelName) {
         var self = this;
         var records = _.map(recordIds, function (id) { return self.localData[id]; });
-        var context = _.extend(records[0].getContext(), session.user_context);
+        var context = Object.assign(records[0].getContext(), session.user_context);
         return this._rpc({
                 model: modelName,
                 method: 'unlink',
@@ -410,7 +410,7 @@ var BasicModel = AbstractModel.extend({
                 if (elem._savePoint instanceof Array) {
                     elem._changes = elem._savePoint.slice(0);
                 } else {
-                    elem._changes = _.extend({}, elem._savePoint);
+                    elem._changes = Object.assign({}, elem._savePoint);
                 }
                 elem._isDirty = !isNew;
             } else {
@@ -621,8 +621,8 @@ var BasicModel = AbstractModel.extend({
         }
 
         var list = {
-            aggregateValues: _.extend({}, element.aggregateValues),
-            context: _.extend({}, element.context),
+            aggregateValues: Object.assign({}, element.aggregateValues),
+            context: Object.assign({}, element.context),
             count: element.count,
             data: _.map(element.data, function (elemID) {
                 return self.__get(elemID, options);
@@ -1119,7 +1119,7 @@ var BasicModel = AbstractModel.extend({
                     if (newValue instanceof Array) {
                         rec._savePoint = newValue.slice(0);
                     } else {
-                        rec._savePoint = _.extend({}, newValue);
+                        rec._savePoint = Object.assign({}, newValue);
                     }
                 });
 
@@ -1190,7 +1190,7 @@ var BasicModel = AbstractModel.extend({
                                     reject,
                                 );
                             } else {
-                                _.extend(record.data, _changes);
+                                Object.assign(record.data, _changes);
                                 resolve(changedFields);
                             }
                         }).guardedCatch(reject);
@@ -1403,7 +1403,7 @@ var BasicModel = AbstractModel.extend({
     unfreezeOrder: function (elementID) {
         var list = this.localData[elementID];
         if (list.type === 'record') {
-            var data = _.extend({}, list.data, list._changes);
+            var data = Object.assign({}, list.data, list._changes);
             for (var fieldName in data) {
                 var field = list.fields[fieldName];
                 if (!field || !data[fieldName]) {
@@ -1561,7 +1561,7 @@ var BasicModel = AbstractModel.extend({
                         resolve(_.keys(changes).concat(Object.keys(result && result.value || {})));
                     }).guardedCatch(function () {
                         self._visitChildren(record, function (elem) {
-                            _.extend(elem, initialData[elem.id]);
+                            Object.assign(elem, initialData[elem.id]);
                         });
                         reject();
                     });
@@ -1806,7 +1806,7 @@ var BasicModel = AbstractModel.extend({
                         // CREATE or UPDATE
                         if (command[0] === 0 && command[1]) {
                             // updating an existing (virtual) record
-                            var previousChange = _.find(oldChanges, function (operation) {
+                            var previousChange = oldChanges.find(operation => {
                                 var child = self.localData[operation.id];
                                 return child && (child.ref === command[1]);
                             });
@@ -2014,7 +2014,7 @@ var BasicModel = AbstractModel.extend({
                         model: list.model,
                         method: 'read',
                         args: [_.pluck(data, 'id'), fieldNames],
-                        context: _.extend({}, record.context, field.context, list.getContext()),
+                        context: Object.assign({}, record.context, field.context, list.getContext()),
                     }).then(function (records) {
                         _.each(records, function (record) {
                             list_records[record.id].data = record;
@@ -2029,7 +2029,7 @@ var BasicModel = AbstractModel.extend({
                 }
                 break;
             case 'CREATE':
-                var createOptions = _.extend({
+                var createOptions = Object.assign({
                     context: command.context,
                     position: command.position
                 }, options || {});
@@ -2517,9 +2517,7 @@ var BasicModel = AbstractModel.extend({
             })
             .then(function (name_gets) {
                 _.each(records, function (record) {
-                    var nameGet = _.find(name_gets, function (nameGet) {
-                        return nameGet[0] === record.data.id;
-                    });
+                    var nameGet = name_gets.find(nameGet => nameGet[0] === record.data.id);
                     record.data.display_name = nameGet[1];
                 });
             });
@@ -2546,14 +2544,14 @@ var BasicModel = AbstractModel.extend({
                 model: record.model,
                 method: 'read',
                 args: [[record.res_id], fieldNames],
-                context: _.extend({bin_size: true}, record.getContext()),
+                context: Object.assign({bin_size: true}, record.getContext()),
             })
             .then(function (result) {
                 if (result.length === 0) {
                     return Promise.reject();
                 }
                 result = result[0];
-                record.data = _.extend({}, record.data, result);
+                record.data = Object.assign({}, record.data, result);
             })
             .then(function () {
                 self._parseServerData(fieldNames, record, record.data);
@@ -3174,9 +3172,9 @@ var BasicModel = AbstractModel.extend({
         var changes;
         const changesOnly = 'changesOnly' in options ? !!options.changesOnly : true;
         if (!changesOnly) {
-            changes = _.extend({}, record.data, record._changes);
+            changes = Object.assign({}, record.data, record._changes);
         } else {
-            changes = _.extend({}, record._changes);
+            changes = Object.assign({}, record._changes);
         }
         var withReadonly = options.withReadonly || false;
         var commands = this._generateX2ManyCommands(record, {
@@ -3231,11 +3229,11 @@ var BasicModel = AbstractModel.extend({
      * @returns {Object} the data
      */
     _generateOnChangeData: function (record, options) {
-        options = _.extend({}, options || {}, {withReadonly: true});
+        options = Object.assign({}, options || {}, {withReadonly: true});
         var data = {};
         if (!options.firstOnChange) {
             var commands = this._generateX2ManyCommands(record, options);
-            data = _.extend(this.get(record.id, {raw: true}).data, commands);
+            data = Object.assign(this.get(record.id, {raw: true}).data, commands);
             // 'display_name' is automatically added to the list of fields to fetch,
             // when fetching a record, even if it doesn't appear in the view. However,
             // only the fields in the view must be passed to the onchange RPC, so we
@@ -3286,7 +3284,7 @@ var BasicModel = AbstractModel.extend({
             fields = _.pick(fields, options.fieldNames);
         }
         var commands = {};
-        var data = _.extend({}, record.data, record._changes);
+        var data = Object.assign({}, record.data, record._changes);
         var type;
         for (var fieldName in fields) {
             type = fields[fieldName].type;
@@ -3851,7 +3849,7 @@ var BasicModel = AbstractModel.extend({
     _getRecordEvalContext: function (record, forDomain) {
         var self = this;
         var relDataPoint;
-        var context = _.extend({}, record.data, record._changes);
+        var context = Object.assign({}, record.data, record._changes);
 
         // calls _generateX2ManyCommands for a given field, and returns the array of commands
         function _generateX2ManyCommands(fieldName) {
@@ -4146,7 +4144,7 @@ var BasicModel = AbstractModel.extend({
         var res_ids = params.res_ids || [];
         var data = params.data || (type === 'record' ? {} : []);
         var context = params.context;
-        var fields = _.extend({
+        var fields = Object.assign({
             display_name: {type: 'char'},
             id: {type: 'integer'},
         }, params.fields);
@@ -4424,7 +4422,7 @@ var BasicModel = AbstractModel.extend({
         var self = this;
 
         // save the RPC request
-        var request = _.extend({}, params);
+        var request = Object.assign({}, params);
         var prom = new Promise(function (resolve, reject) {
             request.resolve = resolve;
             request.reject = reject;
@@ -4449,7 +4447,7 @@ var BasicModel = AbstractModel.extend({
                 var request = batchedRPCsRequests[i];
                 key = request.model + ',' + JSON.stringify(request.context);
                 if (!batches[key]) {
-                    batches[key] = _.extend({}, request, {requests: [request]});
+                    batches[key] = Object.assign({}, request, {requests: [request]});
                 } else {
                     batches[key].ids = _.uniq(batches[key].ids.concat(request.ids));
                     batches[key].fieldNames = _.uniq(batches[key].fieldNames.concat(request.fieldNames));
@@ -4702,7 +4700,7 @@ var BasicModel = AbstractModel.extend({
                 continue;
             }
             var record = self.localData[dataPointID];
-            var data = _.extend({}, record.data, record._changes);
+            var data = Object.assign({}, record.data, record._changes);
             if (_.difference(fieldNames, _.keys(data)).length) {
                 missingIDs.push(resId);
             }
@@ -4730,7 +4728,7 @@ var BasicModel = AbstractModel.extend({
                     dataPoint = self.localData[list._cache[id]];
                     if (data) {
                         self._parseServerData(fieldNames, dataPoint, data);
-                        _.extend(dataPoint.data, data);
+                        Object.assign(dataPoint.data, data);
                     }
                 } else {
                     dataPoint = self._makeDataPoint({
@@ -4815,9 +4813,7 @@ var BasicModel = AbstractModel.extend({
                     // the 'title'.
                     var value = group[groupByField];
                     if (list.fields[rawGroupBy].type === "selection") {
-                        var choice = _.find(list.fields[rawGroupBy].selection, function (c) {
-                            return c[0] === value;
-                        });
+                        var choice = list.fields[rawGroupBy].selection.find(c => c[0] === value);
                         value = choice ? choice[1] : false;
                     }
                     var newGroup = self._makeDataPoint({
@@ -4839,9 +4835,7 @@ var BasicModel = AbstractModel.extend({
                         type: 'list',
                         viewType: list.viewType,
                     });
-                    var oldGroup = _.find(previousGroups, function (g) {
-                        return g.res_id === newGroup.res_id && g.value === newGroup.value;
-                    });
+                    var oldGroup = previousGroups.find(g => g.res_id === newGroup.res_id && g.value === newGroup.value);
                     if (oldGroup) {
                         delete self.localData[newGroup.id];
                         // restore the internal state of the group
@@ -5122,7 +5116,7 @@ var BasicModel = AbstractModel.extend({
                 route: '/web/dataset/search_read',
                 model: list.model,
                 fields: fieldNames,
-                context: _.extend({}, list.getContext(), {bin_size: true}),
+                context: Object.assign({}, list.getContext(), {bin_size: true}),
                 domain: this._getUngroupedListDomain(list),
                 limit: list.limit,
                 offset: list.loadMoreOffset + list.offset,
@@ -5264,8 +5258,8 @@ var BasicModel = AbstractModel.extend({
                 }
                 var r1 = self.localData[record1ID];
                 var r2 = self.localData[record2ID];
-                var data1 = _.extend({}, r1.data, r1._changes);
-                var data2 = _.extend({}, r2.data, r2._changes);
+                var data1 = Object.assign({}, r1.data, r1._changes);
+                var data2 = Object.assign({}, r2.data, r2._changes);
 
                 // Default value to sort against: the value of the field
                 var orderData1 = data1[order.name];
diff --git a/addons/web/static/src/legacy/js/views/standalone_field_manager_mixin.js b/addons/web/static/src/legacy/js/views/standalone_field_manager_mixin.js
index 73a677841d7..5d0a1f08d65 100644
--- a/addons/web/static/src/legacy/js/views/standalone_field_manager_mixin.js
+++ b/addons/web/static/src/legacy/js/views/standalone_field_manager_mixin.js
@@ -12,7 +12,7 @@ import FieldManagerMixin from 'web.FieldManagerMixin';
  * @property {Function} _confirmChange
  * @property {Function} _registerWidget
  */
-var StandaloneFieldManagerMixin = _.extend({}, FieldManagerMixin, {
+var StandaloneFieldManagerMixin = Object.assign({}, FieldManagerMixin, {
 
     /**
      * @override
diff --git a/addons/web/static/src/legacy/js/views/view_utils.js b/addons/web/static/src/legacy/js/views/view_utils.js
index 50a3200afee..26db6e11047 100644
--- a/addons/web/static/src/legacy/js/views/view_utils.js
+++ b/addons/web/static/src/legacy/js/views/view_utils.js
@@ -31,9 +31,7 @@ var viewUtils = {
             case 'many2one':
                 return group.res_id || false;
             case 'selection':
-                var descriptor = _.find(groupedByField.selection, function (option) {
-                    return option[1] === group.value;
-                });
+                var descriptor = groupedByField.selection.find(option => option[1] === group.value);
                 return descriptor && descriptor[0];
             case 'char':
             case 'boolean':
diff --git a/addons/web/static/src/legacy/js/widgets/colorpicker.js b/addons/web/static/src/legacy/js/widgets/colorpicker.js
index ca7e675692b..bb307e55827 100644
--- a/addons/web/static/src/legacy/js/widgets/colorpicker.js
+++ b/addons/web/static/src/legacy/js/widgets/colorpicker.js
@@ -177,7 +177,7 @@ var ColorpickerWidget = Widget.extend({
         if (!rgb) {
             return;
         }
-        _.extend(this.colorComponents,
+        Object.assign(this.colorComponents,
             {hex: hex},
             rgb,
             ColorpickerWidget.convertRgbToHsl(rgb.red, rgb.green, rgb.blue)
@@ -207,7 +207,7 @@ var ColorpickerWidget = Widget.extend({
         if (!hex) {
             return;
         }
-        _.extend(this.colorComponents,
+        Object.assign(this.colorComponents,
             {red: r, green: g, blue: b},
             a === undefined ? {} : {opacity: a},
             {hex: hex},
@@ -236,7 +236,7 @@ var ColorpickerWidget = Widget.extend({
         }
         // We receive an hexa as we ignore the opacity
         const hex = ColorpickerWidget.convertRgbaToCSSColor(rgb.red, rgb.green, rgb.blue);
-        _.extend(this.colorComponents,
+        Object.assign(this.colorComponents,
             {hue: h, saturation: s, lightness: l},
             rgb,
             {hex: hex},
@@ -254,7 +254,7 @@ var ColorpickerWidget = Widget.extend({
         if (a < 0 || a > 100) {
             return;
         }
-        _.extend(this.colorComponents,
+        Object.assign(this.colorComponents,
             {opacity: a}
         );
         this._updateCssColor();
@@ -277,7 +277,7 @@ var ColorpickerWidget = Widget.extend({
         const g = this.colorComponents.green;
         const b = this.colorComponents.blue;
         const a = this.colorComponents.opacity;
-        _.extend(this.colorComponents,
+        Object.assign(this.colorComponents,
             {cssColor: ColorpickerWidget.convertRgbaToCSSColor(r, g, b, a)}
         );
         if (this.previewActive) {
@@ -702,7 +702,7 @@ const ColorpickerDialog = Dialog.extend({
      */
     init: function (parent, options) {
         this.options = options || {};
-        this._super(parent, _.extend({
+        this._super(parent, Object.assign({
             size: 'small',
             title: _t('Pick a color'),
             buttons: [
@@ -716,7 +716,7 @@ const ColorpickerDialog = Dialog.extend({
      */
     start: function () {
         const proms = [this._super(...arguments)];
-        this.colorPicker = new ColorpickerWidget(this, _.extend({
+        this.colorPicker = new ColorpickerWidget(this, Object.assign({
             colorPreview: true,
         }, this.options));
         proms.push(this.colorPicker.appendTo(this.$el));
diff --git a/addons/web/static/src/legacy/js/widgets/date_picker.js b/addons/web/static/src/legacy/js/widgets/date_picker.js
index b73dee9a6ba..2d0bcba07b9 100644
--- a/addons/web/static/src/legacy/js/widgets/date_picker.js
+++ b/addons/web/static/src/legacy/js/widgets/date_picker.js
@@ -26,7 +26,7 @@ var DateWidget = Widget.extend({
         this._super.apply(this, arguments);
 
         this.name = parent.name;
-        this.options = _.extend({
+        this.options = Object.assign({
             locale: moment.locale(),
             format : this.type_of_date === 'datetime' ? time.getLangDatetimeFormat() : time.getLangDateFormat(),
             minDate: moment({ y: 1000 }),
@@ -339,7 +339,7 @@ var DateWidget = Widget.extend({
 var DateTimeWidget = DateWidget.extend({
     type_of_date: "datetime",
     init: function (parent, options) {
-        this._super(parent, _.extend({
+        this._super(parent, Object.assign({
             buttons: {
                 showToday: false,
                 showClear: false,
diff --git a/addons/web/static/src/legacy/js/widgets/domain_selector.js b/addons/web/static/src/legacy/js/widgets/domain_selector.js
index ac9e33fc58b..8183fc5115d 100644
--- a/addons/web/static/src/legacy/js/widgets/domain_selector.js
+++ b/addons/web/static/src/legacy/js/widgets/domain_selector.js
@@ -71,7 +71,7 @@ var DomainNode = Widget.extend({
         this._super.apply(this, arguments);
 
         this.model = model;
-        this.options = _.extend({
+        this.options = Object.assign({
             readonly: true,
             operators: null,
             debugMode: false,
@@ -162,7 +162,7 @@ var DomainNode = Widget.extend({
  */
 var DomainTree = DomainNode.extend({
     template: "DomainTree",
-    events: _.extend({}, DomainNode.prototype.events, {
+    events: Object.assign({}, DomainNode.prototype.events, {
         "click .o_domain_tree_operator_selector .dropdown-item": "_onOperatorChange",
     }),
     custom_events: {
@@ -461,11 +461,11 @@ var DomainTree = DomainNode.extend({
  */
 var DomainSelector = DomainTree.extend({
     template: "DomainSelector",
-    events: _.extend({}, DomainTree.prototype.events, {
+    events: Object.assign({}, DomainTree.prototype.events, {
         "click .o_domain_add_first_node_button": "_onAddFirstButtonClick",
         "change .o_domain_debug_input": "_onDebugInputChange",
     }),
-    custom_events: _.extend({}, DomainTree.prototype.custom_events, {
+    custom_events: Object.assign({}, DomainTree.prototype.custom_events, {
         domain_changed: "_onDomainChange",
     }),
 
@@ -637,7 +637,7 @@ var DomainSelector = DomainTree.extend({
  */
 var DomainLeaf = DomainNode.extend({
     template: "DomainLeaf",
-    events: _.extend({}, DomainNode.prototype.events, {
+    events: Object.assign({}, DomainNode.prototype.events, {
         "change .o_domain_leaf_operator_select": "_onOperatorSelectChange",
         "change .o_domain_leaf_value_input": "_onValueInputChange",
 
@@ -922,7 +922,7 @@ var DomainLeaf = DomainNode.extend({
                 break;
 
             default:
-                operators = _.extend({}, operator_mapping);
+                operators = Object.assign({}, operator_mapping);
                 break;
         }
 
diff --git a/addons/web/static/src/legacy/js/widgets/domain_selector_dialog.js b/addons/web/static/src/legacy/js/widgets/domain_selector_dialog.js
index a6d453351c1..ab3566b8a20 100644
--- a/addons/web/static/src/legacy/js/widgets/domain_selector_dialog.js
+++ b/addons/web/static/src/legacy/js/widgets/domain_selector_dialog.js
@@ -11,13 +11,13 @@ var _t = core._t;
  * @class DomainSelectorDialog
  */
 export default Dialog.extend({
-    custom_events: _.extend({}, Dialog.prototype.custom_events, {
+    custom_events: Object.assign({}, Dialog.prototype.custom_events, {
         domain_changed: "_onDomainChange",
     }),
     init: function (parent, model, domain, options) {
         this.model = model;
         this.newDomain = null;
-        this.options = _.extend({
+        this.options = Object.assign({
             readonly: true,
             debugMode: false,
         }, options || {});
@@ -38,7 +38,7 @@ export default Dialog.extend({
             ];
         }
 
-        this._super(parent, _.extend({}, {
+        this._super(parent, Object.assign({}, {
             title: _t("Domain"),
             buttons: buttons,
         }, options || {}));
diff --git a/addons/web/static/src/legacy/js/widgets/model_field_selector.js b/addons/web/static/src/legacy/js/widgets/model_field_selector.js
index 5719a8d167c..bfbe3049f16 100644
--- a/addons/web/static/src/legacy/js/widgets/model_field_selector.js
+++ b/addons/web/static/src/legacy/js/widgets/model_field_selector.js
@@ -56,7 +56,7 @@ var ModelFieldSelector = Widget.extend({
 
         this.model = model;
         this.chain = chain;
-        this.options = _.extend({
+        this.options = Object.assign({
             order: 'string',
             readonly: true,
             fields: null,
@@ -67,7 +67,7 @@ var ModelFieldSelector = Widget.extend({
         this.popover = new ModelFieldSelectorPopover(this, model, chain, options);
 
         if (!this.options.readonly) {
-            _.extend(this.events, this.edition_events);
+            Object.assign(this.events, this.edition_events);
         }
     },
     /**
diff --git a/addons/web/static/src/legacy/js/widgets/model_field_selector_popover.js b/addons/web/static/src/legacy/js/widgets/model_field_selector_popover.js
index 3b71d1890e2..81752970b23 100644
--- a/addons/web/static/src/legacy/js/widgets/model_field_selector_popover.js
+++ b/addons/web/static/src/legacy/js/widgets/model_field_selector_popover.js
@@ -86,7 +86,7 @@ var ModelFieldSelectorPopover = Widget.extend({
 
         this.model = model;
         this.chain = chain;
-        this.options = _.extend({
+        this.options = Object.assign({
             order: 'string',
             filters: {},
             fields: null,
@@ -98,7 +98,7 @@ var ModelFieldSelectorPopover = Widget.extend({
             cancelOnEscape: false,
             chainedTitle: false
         }, options || {});
-        this.options.filters = _.extend({
+        this.options.filters = Object.assign({
             searchable: true,
         }, this.options.filters);
 
@@ -149,7 +149,7 @@ var ModelFieldSelectorPopover = Widget.extend({
      * @returns {Object}
      */
     getSelectedField: function () {
-        return _.findWhere(this.pages[this.chain.length - 1], {name: _.last(this.chain)});
+        return _.findWhere(this.pages[this.chain.length - 1], {name: this.chain.at(-1)});
     },
     /**
      * Saves a new field chain (array) and re-render.
@@ -213,7 +213,7 @@ var ModelFieldSelectorPopover = Widget.extend({
      *                   to its name
      /*/
     _getLastPageField: function (name) {
-        return _.findWhere(_.last(this.pages), {
+        return _.findWhere(this.pages.at(-1) , {
             name: name,
         });
     },
@@ -404,10 +404,10 @@ var ModelFieldSelectorPopover = Widget.extend({
         var title = "";
         if (this.pages.length > 1) {
             var prevField = _.findWhere(this.pages[this.pages.length - 2], {
-                name: (this.chain.length === this.pages.length) ? this.chain[this.chain.length - 2] : _.last(this.chain),
+                name: (this.chain.length === this.pages.length) ? this.chain[this.chain.length - 2] : this.chain.at(-1),
             });
             if (prevField) {
-                this.titlesNames[_.last(this.chain)] = prevField.string;
+                this.titlesNames[this.chain.at(-1)] = prevField.string;
                 title = prevField.string;
             }
         }
@@ -426,7 +426,7 @@ var ModelFieldSelectorPopover = Widget.extend({
         this._adaptInputVisibility();
 
         // Adapt the popover content
-        var page = _.last(this.pages);
+        var page = this.pages.at(-1);
         this.$(".o_field_selector_popover_header .o_field_selector_title").text(this._getTitle());
 
         var lines = _.filter(page, this.options.filter);
@@ -722,7 +722,7 @@ function sortFields(fields, model, order) {
         array = array.sortBy(function (p) {return p[1][order]; });
     }
     return array.map(function (p) {
-            return _.extend({
+            return Object.assign({
                 name: p[0],
                 model: model,
             }, p[1]);
diff --git a/addons/web/static/src/legacy/js/widgets/name_and_signature.js b/addons/web/static/src/legacy/js/widgets/name_and_signature.js
index d611aae55a3..a7a97ea6088 100644
--- a/addons/web/static/src/legacy/js/widgets/name_and_signature.js
+++ b/addons/web/static/src/legacy/js/widgets/name_and_signature.js
@@ -423,7 +423,7 @@ var NameAndSignature = Widget.extend({
                 }
                 self.$signatureField.jSignature('reset');
                 var ignoredContext = _.pick(context, ['shadowOffsetX', 'shadowOffsetY']);
-                _.extend(context, {shadowOffsetX: 0, shadowOffsetY: 0});
+                Object.assign(context, {shadowOffsetX: 0, shadowOffsetY: 0});
                 context.drawImage(image,
                     0,
                     0,
@@ -434,7 +434,7 @@ var NameAndSignature = Widget.extend({
                     width,
                     height
                 );
-                _.extend(context, ignoredContext);
+                Object.assign(context, ignoredContext);
                 self.trigger_up('signature_changed');
             }, 0);
         };
diff --git a/addons/web/static/tests/legacy/core/domain_tests.js b/addons/web/static/tests/legacy/core/domain_tests.js
index 8f6ec255b5d..52df7d8c524 100644
--- a/addons/web/static/tests/legacy/core/domain_tests.js
+++ b/addons/web/static/tests/legacy/core/domain_tests.js
@@ -40,9 +40,9 @@ QUnit.module('core', {}, function () {
                     ['user_id', '=', 3],
                     ['member_ids', 'in', [3]]
         ];
-        assert.ok(new Domain(currentDomain).compute(_.extend({}, web, {section_id: 42})));
-        assert.ok(new Domain(currentDomain).compute(_.extend({}, web, {user_id: 3})));
-        assert.ok(new Domain(currentDomain).compute(_.extend({}, web, {member_ids: 3})));
+        assert.ok(new Domain(currentDomain).compute(Object.assign({}, web, {section_id: 42})));
+        assert.ok(new Domain(currentDomain).compute(Object.assign({}, web, {user_id: 3})));
+        assert.ok(new Domain(currentDomain).compute(Object.assign({}, web, {member_ids: 3})));
     });
 
     QUnit.test("not", function (assert) {
diff --git a/addons/web/static/tests/legacy/core/py_utils_tests.js b/addons/web/static/tests/legacy/core/py_utils_tests.js
index 4fe4a729ca3..a804d2d35a3 100644
--- a/addons/web/static/tests/legacy/core/py_utils_tests.js
+++ b/addons/web/static/tests/legacy/core/py_utils_tests.js
@@ -66,7 +66,7 @@ QUnit.module('core', function () {
     // Port from pypy/lib_pypy/test_datetime.py
     function makeEq(assert, c2) {
         var ctx = pyUtils.context();
-        var c = _.extend({ td: ctx.datetime.timedelta }, c2 || {});
+        var c = Object.assign({ td: ctx.datetime.timedelta }, c2 || {});
         return function (a, b, message) {
             assert.ok(py.eval(a + ' == ' + b, c), message);
         };
diff --git a/addons/web/static/tests/legacy/helpers/mock_server.js b/addons/web/static/tests/legacy/helpers/mock_server.js
index 0051c9f7655..b792c9d44ef 100644
--- a/addons/web/static/tests/legacy/helpers/mock_server.js
+++ b/addons/web/static/tests/legacy/helpers/mock_server.js
@@ -362,7 +362,7 @@ var MockServer = Class.extend({
             var attrs = node.getAttribute('attrs');
             if (attrs) {
                 attrs = pyUtils.py_eval(attrs);
-                _.extend(modifiers, attrs);
+                Object.assign(modifiers, attrs);
             }
 
             var states = node.getAttribute('states');
@@ -422,7 +422,7 @@ var MockServer = Class.extend({
                         // this is hackhish, but _getView modifies the subview document in place,
                         // especially to generate the "modifiers" attribute
                         const { models } = self._getView(childNode, relModel,
-                            relFields, _.extend({}, context, {base_model_name: model}));
+                            relFields, Object.assign({}, context, {base_model_name: model}));
                         [...models].forEach((modelName) => relatedModels.add(modelName));
                     }
                 });
@@ -570,7 +570,7 @@ var MockServer = Class.extend({
         var model = this.data[modelName];
         var newID = this._getUnusedID(modelName);
         var originalRecord = _.findWhere(model.records, {id: id});
-        var duplicateRecord = _.extend({}, originalRecord, {id: newID});
+        var duplicateRecord = Object.assign({}, originalRecord, {id: newID});
         duplicateRecord.display_name = originalRecord.display_name + ' (copy)';
         model.records.push(duplicateRecord);
         return newID;
diff --git a/addons/web/static/tests/legacy/helpers/test_utils_mock.js b/addons/web/static/tests/legacy/helpers/test_utils_mock.js
index 23311be2de0..22aded6025c 100644
--- a/addons/web/static/tests/legacy/helpers/test_utils_mock.js
+++ b/addons/web/static/tests/legacy/helpers/test_utils_mock.js
@@ -218,13 +218,13 @@ function _mockGlobalObjects(params) {
             for (key in config) {
                 delete config[key];
             }
-            _.extend(config, initialConfig);
+            Object.assign(config, initialConfig);
         }
         if ('translateParameters' in params) {
             for (key in core._t.database.parameters) {
                 delete core._t.database.parameters[key];
             }
-            _.extend(core._t.database.parameters, initialParameters);
+            Object.assign(core._t.database.parameters, initialParameters);
         }
     }
 
diff --git a/addons/web/static/tests/legacy/owl_compatibility_tests.js b/addons/web/static/tests/legacy/owl_compatibility_tests.js
index 3d0b7ff85a1..9a398020ab3 100644
--- a/addons/web/static/tests/legacy/owl_compatibility_tests.js
+++ b/addons/web/static/tests/legacy/owl_compatibility_tests.js
@@ -1442,7 +1442,7 @@
             WidgetComponent.template = xml`<div>Component</div>`;
 
             const MyWidget = WidgetAdapter.extend({
-                custom_events: _.extend({}, Widget.custom_events, {
+                custom_events: Object.assign({}, Widget.custom_events, {
                     some_event: function (ev) {
                         assert.step(ev.data.value);
                     }
@@ -1474,7 +1474,7 @@
             class WidgetComponent extends LegacyComponent {}
             WidgetComponent.template = xml`<div>Component</div>`;
             const MyWidget = WidgetAdapter.extend({
-                custom_events: _.extend({}, Widget.custom_events, {
+                custom_events: Object.assign({}, Widget.custom_events, {
                     some_event: function (ev) {
                         assert.strictEqual(this, ev.data.widget);
                         assert.step(ev.data.value);
diff --git a/addons/web/static/tests/legacy/qweb_tests.js b/addons/web/static/tests/legacy/qweb_tests.js
index 8e9f3cc80d3..044eb613b32 100644
--- a/addons/web/static/tests/legacy/qweb_tests.js
+++ b/addons/web/static/tests/legacy/qweb_tests.js
@@ -79,7 +79,7 @@ const table = [
         fixture: {
             before() {
                 this.WORD_REPLACEMENT = window.QWeb2.WORD_REPLACEMENT;
-                window.QWeb2.WORD_REPLACEMENT = _.extend(
+                window.QWeb2.WORD_REPLACEMENT = Object.assign(
                     {not: '!', None: 'undefined'},
                     this.WORD_REPLACEMENT
                 )
diff --git a/addons/web/static/tests/legacy/views/basic_model_tests.js b/addons/web/static/tests/legacy/views/basic_model_tests.js
index 7c6250cefa7..41608d6be1b 100644
--- a/addons/web/static/tests/legacy/views/basic_model_tests.js
+++ b/addons/web/static/tests/legacy/views/basic_model_tests.js
@@ -98,7 +98,7 @@
                     return this._super.apply(this, arguments);
                 },
             });
-            const params = _.extend(this.params, {
+            const params = Object.assign(this.params, {
                 context: { active_field: 2 },
                 groupedBy: ['product_id'],
                 fieldNames: ['foo'],
@@ -825,7 +825,7 @@
 
             var rpcCount = 0;
             var fields = this.data.partner.fields;
-            fields.other_product_id = _.extend({}, fields.product_id);
+            fields.other_product_id = Object.assign({}, fields.product_id);
             fields.product_id.default = 37;
             fields.other_product_id.default = 41;
 
@@ -1995,7 +1995,7 @@
             });
 
             // load a new record (default_get)
-            var params = _.extend(this.params, {
+            var params = Object.assign(this.params, {
                 res_id: undefined,
                 type: 'record',
                 fieldNames: ['foo'],
@@ -2195,7 +2195,7 @@
                     string: 'foobool2',
                 },
             };
-            _.extend(this.data.partner.fields, newFields);
+            Object.assign(this.data.partner.fields, newFields);
 
             this.data.partner.fields.foobool.onChange = true;
             this.data.partner.onchanges.foobool = function (obj) {
diff --git a/addons/web/static/tests/views/fields/badge_selection_field_tests.js b/addons/web/static/tests/views/fields/badge_selection_field_tests.js
index 97714fdca41..8f767a8d39f 100644
--- a/addons/web/static/tests/views/fields/badge_selection_field_tests.js
+++ b/addons/web/static/tests/views/fields/badge_selection_field_tests.js
@@ -91,7 +91,7 @@ QUnit.module("Fields", (hooks) => {
 
         await click(target, ".o_form_button_save");
 
-        var newRecord = _.last(serverData.models.partner.records);
+        var newRecord = serverData.models.partner.records.at(-1);
         assert.strictEqual(newRecord.product_id, 37, "should have saved record with correct value");
     });
 
@@ -122,7 +122,7 @@ QUnit.module("Fields", (hooks) => {
 
             await click(target.querySelector(".o_form_button_save"));
 
-            var newRecord = _.last(serverData.models.partner.records);
+            var newRecord = serverData.models.partner.records.at(-1);
             assert.strictEqual(
                 newRecord.color,
                 "black",
diff --git a/addons/web/static/tests/views/fields/many2many_field_tests.js b/addons/web/static/tests/views/fields/many2many_field_tests.js
index beafde32329..8b66bae6d63 100644
--- a/addons/web/static/tests/views/fields/many2many_field_tests.js
+++ b/addons/web/static/tests/views/fields/many2many_field_tests.js
@@ -817,7 +817,7 @@ QUnit.module("Fields", (hooks) => {
                 </form>`,
             mockRPC(route, args) {
                 if (args.method !== "get_views") {
-                    assert.step(_.last(route.split("/")));
+                    assert.step(route.split("/").at(-1));
                 }
                 if (args.method === "write") {
                     assert.deepEqual(args.args[1].timmy, [
@@ -1424,7 +1424,7 @@ QUnit.module("Fields", (hooks) => {
             resId: 1,
             mockRPC(route, args) {
                 if (args.method !== "get_views") {
-                    assert.step(_.last(route.split("/")) + " on " + args.model);
+                    assert.step(route.split("/").at(-1) + " on " + args.model);
                 }
                 if (args.model === "turtle") {
                     assert.step(JSON.stringify(args.args[0])); // the read ids
diff --git a/addons/web/static/tests/views/kanban_view_tests.js b/addons/web/static/tests/views/kanban_view_tests.js
index 4c8e950ed83..323aa2ac8bc 100644
--- a/addons/web/static/tests/views/kanban_view_tests.js
+++ b/addons/web/static/tests/views/kanban_view_tests.js
@@ -3467,7 +3467,7 @@ QUnit.module("Views", (hooks) => {
             "should have created a partner"
         );
         assert.strictEqual(
-            _.last(serverData.models.partner.records).name,
+            serverData.models.partner.records.at(-1).name,
             "new partner",
             "should have correct name"
         );
diff --git a/addons/web/static/tests/views/list_view_tests.js b/addons/web/static/tests/views/list_view_tests.js
index cf168dd2e28..745d3dfa269 100644
--- a/addons/web/static/tests/views/list_view_tests.js
+++ b/addons/web/static/tests/views/list_view_tests.js
@@ -9752,7 +9752,7 @@ QUnit.module("Views", (hooks) => {
             // create records to have the search more button
             const newRecs = [];
             for (let i = 0; i < 8; i++) {
-                const newRec = _.extend({}, rec);
+                const newRec = Object.assign({}, rec);
                 newRec.id = 1 + i;
                 newRec.cornichon = "extra fin";
                 newRecs.push(newRec);
diff --git a/addons/web_editor/static/src/js/common/ace.js b/addons/web_editor/static/src/js/common/ace.js
index 8326c4a55ff..8faac6b9e7d 100644
--- a/addons/web_editor/static/src/js/common/ace.js
+++ b/addons/web_editor/static/src/js/common/ace.js
@@ -518,7 +518,7 @@ var ViewEditor = Widget.extend({
 
         function _processViews(views) {
             // Only keep the active views and index them by ID.
-            _.extend(this.views, _.indexBy(_.filter(views, function (view) {
+            Object.assign(this.views, _.indexBy(_.filter(views, function (view) {
                 return view.active;
             }), 'id'));
 
@@ -566,7 +566,7 @@ var ViewEditor = Widget.extend({
             var resources = type === 'scss' ? this.scss : this.js;
             _.each(data, function (bundleInfos) {
                 _.each(bundleInfos[1], function (info) { info.bundle = bundleInfos[0]; });
-                _.extend(resources, _.indexBy(bundleInfos[1], 'url'));
+                Object.assign(resources, _.indexBy(bundleInfos[1], 'url'));
             });
         }
     },
diff --git a/addons/web_editor/static/src/js/editor/snippets.editor.js b/addons/web_editor/static/src/js/editor/snippets.editor.js
index bc321119fbd..cc7a170b2d0 100644
--- a/addons/web_editor/static/src/js/editor/snippets.editor.js
+++ b/addons/web_editor/static/src/js/editor/snippets.editor.js
@@ -807,7 +807,7 @@ var SnippetEditor = Widget.extend({
                 val.$el.children(),
                 val.base_target ? this.$target.find(val.base_target).eq(0) : this.$target,
                 this.$el,
-                _.extend({
+                Object.assign({
                     optionName: optionName,
                     snippetName: this.getName(),
                 }, val.data),
@@ -2804,7 +2804,7 @@ var SnippetsMenu = Widget.extend({
                 '$el': $style,
                 'drop-near': $style.data('drop-near') && self._computeSelectorFunctions($style.data('drop-near'), '', false, noCheck, true, excludeParent),
                 'drop-in': $style.data('drop-in') && self._computeSelectorFunctions($style.data('drop-in'), '', false, noCheck),
-                'data': _.extend({string: $style.attr('string')}, $style.data()),
+                'data': Object.assign({string: $style.attr('string')}, $style.data()),
             };
             self.templateOptions.push(option);
             selectors.push(option.selector);
diff --git a/addons/web_editor/static/src/js/editor/snippets.options.js b/addons/web_editor/static/src/js/editor/snippets.options.js
index ee9604e7d09..885a324b4c3 100644
--- a/addons/web_editor/static/src/js/editor/snippets.options.js
+++ b/addons/web_editor/static/src/js/editor/snippets.options.js
@@ -402,7 +402,7 @@ const UserValueWidget = Widget.extend({
      * @returns {Object}
      */
     getMethodsParams: function (methodName) {
-        const params = _.extend({}, this._methodsParams);
+        const params = Object.assign({}, this._methodsParams);
         if (methodName) {
             params.possibleValues = params.optionsPossibleValues[methodName] || [];
             params.activeValue = this.getActiveValue(methodName);
@@ -472,7 +472,7 @@ const UserValueWidget = Widget.extend({
      */
     loadMethodsData: function (validMethodNames, extraParams) {
         this._methodsNames = [];
-        this._methodsParams = _.extend({}, extraParams);
+        this._methodsParams = Object.assign({}, extraParams);
         this._methodsParams.optionsPossibleValues = {};
         this._dependencies = [];
         this._triggerWidgetsNames = [];
@@ -495,7 +495,7 @@ const UserValueWidget = Widget.extend({
             }
         }
         this._userValueWidgets.forEach(widget => {
-            const inheritedParams = _.extend({}, this._methodsParams);
+            const inheritedParams = Object.assign({}, this._methodsParams);
             inheritedParams.optionsPossibleValues = null;
             widget.loadMethodsData(validMethodNames, inheritedParams);
             const subMethodsNames = widget.getMethodsNames();
@@ -1388,7 +1388,7 @@ const MultiUserValueWidget = UserValueWidget.extend({
 
 const ColorpickerUserValueWidget = SelectUserValueWidget.extend({
     className: (SelectUserValueWidget.prototype.className || '') + ' o_we_so_color_palette',
-    custom_events: _.extend({}, SelectUserValueWidget.prototype.custom_events, {
+    custom_events: Object.assign({}, SelectUserValueWidget.prototype.custom_events, {
         'custom_color_picked': '_onCustomColorPicked',
         'color_picked': '_onColorPicked',
         'color_hover': '_onColorHovered',
@@ -1458,7 +1458,7 @@ const ColorpickerUserValueWidget = SelectUserValueWidget.extend({
      * @override
      */
     getMethodsParams: function () {
-        return _.extend(this._super(...arguments), {
+        return Object.assign(this._super(...arguments), {
             colorNames: this.colorPalette.getColorNames(),
         });
     },
@@ -1883,7 +1883,7 @@ const DatetimePickerUserValueWidget = InputUserValueWidget.extend({
      * @override
      */
     getMethodsParams: function () {
-        return _.extend(this._super(...arguments), {
+        return Object.assign(this._super(...arguments), {
             format: this.defaultFormat,
         });
     },
@@ -2011,7 +2011,7 @@ const ListUserValueWidget = UserValueWidget.extend({
      * @override
      */
     getMethodsParams() {
-        return _.extend(this._super(...arguments), {
+        return Object.assign(this._super(...arguments), {
             records: this.records,
         });
     },
diff --git a/addons/web_editor/static/src/js/wysiwyg/dialog.js b/addons/web_editor/static/src/js/wysiwyg/dialog.js
index 4561ed70900..e1321f478a2 100644
--- a/addons/web_editor/static/src/js/wysiwyg/dialog.js
+++ b/addons/web_editor/static/src/js/wysiwyg/dialog.js
@@ -18,7 +18,7 @@ var WysiwygDialog = Dialog.extend({
         if (config.device.isMobile) {
             options.fullscreen = true;
         }
-        this._super(parent, _.extend({}, {
+        this._super(parent, Object.assign({}, {
             buttons: [{
                     text: this.options.save_text || _t("Save"),
                     classes: 'btn-primary',
diff --git a/addons/web_editor/static/src/js/wysiwyg/widgets/alt_dialog.js b/addons/web_editor/static/src/js/wysiwyg/widgets/alt_dialog.js
index 2b70f7d1260..5eb46a6c8fb 100644
--- a/addons/web_editor/static/src/js/wysiwyg/widgets/alt_dialog.js
+++ b/addons/web_editor/static/src/js/wysiwyg/widgets/alt_dialog.js
@@ -15,7 +15,7 @@ var AltDialog = Dialog.extend({
      */
     init: function (parent, options, media) {
         options = options || {};
-        this._super(parent, _.extend({}, {
+        this._super(parent, Object.assign({}, {
             title: _t("Change media description and tooltip")
         }, options));
 
diff --git a/addons/web_editor/static/src/js/wysiwyg/widgets/color_palette.js b/addons/web_editor/static/src/js/wysiwyg/widgets/color_palette.js
index c64a6466a54..1c17858fe9f 100644
--- a/addons/web_editor/static/src/js/wysiwyg/widgets/color_palette.js
+++ b/addons/web_editor/static/src/js/wysiwyg/widgets/color_palette.js
@@ -49,7 +49,7 @@ const ColorPaletteWidget = Widget.extend({
         this._super.apply(this, arguments);
         const editableDocument = options.editable ? options.editable.ownerDocument : document;
         this.style = editableDocument.defaultView.getComputedStyle(editableDocument.documentElement);
-        this.options = _.extend({
+        this.options = Object.assign({
             selectedColor: false,
             resetButton: true,
             excluded: [],
diff --git a/addons/web_editor/static/src/js/wysiwyg/widgets/link.js b/addons/web_editor/static/src/js/wysiwyg/widgets/link.js
index e44ce25c1e9..4249964a0d9 100644
--- a/addons/web_editor/static/src/js/wysiwyg/widgets/link.js
+++ b/addons/web_editor/static/src/js/wysiwyg/widgets/link.js
@@ -26,7 +26,7 @@ const Link = Widget.extend({
      */
     init: function (parent, options, editable, data, $button, link) {
         this.options = options || {};
-        this._super(parent, _.extend({
+        this._super(parent, Object.assign({
             title: _t("Link to"),
         }, this.options));
 
diff --git a/addons/web_editor/static/src/js/wysiwyg/widgets/link_dialog.js b/addons/web_editor/static/src/js/wysiwyg/widgets/link_dialog.js
index 413797d5034..0ac334c69b2 100644
--- a/addons/web_editor/static/src/js/wysiwyg/widgets/link_dialog.js
+++ b/addons/web_editor/static/src/js/wysiwyg/widgets/link_dialog.js
@@ -7,7 +7,7 @@ import Link from "wysiwyg.widgets.Link";
 // This widget is there only to extend Link and be instantiated by LinkDialog.
 const _DialogLinkWidget = Link.extend({
     template: 'wysiwyg.widgets.link',
-    events: _.extend({}, Link.prototype.events || {}, {
+    events: Object.assign({}, Link.prototype.events || {}, {
         'change [name="link_style_color"]': '_onTypeChange',
     }),
 
diff --git a/addons/web_editor/static/src/js/wysiwyg/widgets/link_tools.js b/addons/web_editor/static/src/js/wysiwyg/widgets/link_tools.js
index 32994be816d..5c35610fec0 100644
--- a/addons/web_editor/static/src/js/wysiwyg/widgets/link_tools.js
+++ b/addons/web_editor/static/src/js/wysiwyg/widgets/link_tools.js
@@ -16,7 +16,7 @@ import {
  */
 const LinkTools = Link.extend({
     template: 'wysiwyg.widgets.linkTools',
-    events: _.extend({}, Link.prototype.events, {
+    events: Object.assign({}, Link.prototype.events, {
         'click we-select we-button': '_onPickSelectOption',
         'click we-checkbox': '_onClickCheckbox',
         'change .link-custom-color-border input': '_onChangeCustomBorderWidth',
diff --git a/addons/web_editor/static/tests/test_utils.js b/addons/web_editor/static/tests/test_utils.js
index 9413564565b..7827ca43ee6 100644
--- a/addons/web_editor/static/tests/test_utils.js
+++ b/addons/web_editor/static/tests/test_utils.js
@@ -295,7 +295,7 @@ async function createWysiwyg(params) {
     var parent = new Widget();
     await testUtils.mock.addMockEnvironment(parent, params);
 
-    var wysiwygOptions = _.extend({}, params.wysiwygOptions, {
+    var wysiwygOptions = Object.assign({}, params.wysiwygOptions, {
         recordInfo: {
             context: {},
             res_model: 'module.test',
diff --git a/addons/website/static/src/js/content/snippets.animation.js b/addons/website/static/src/js/content/snippets.animation.js
index c4f645365d4..9c1e0bd083b 100644
--- a/addons/website/static/src/js/content/snippets.animation.js
+++ b/addons/website/static/src/js/content/snippets.animation.js
@@ -79,7 +79,7 @@ publicWidget.Widget.include({
         this.editableMode = this.options.editableMode || false;
         var extraEvents = this.editableMode ? this.edit_events : this.read_events;
         if (extraEvents) {
-            this.events = _.extend({}, this.events || {}, extraEvents);
+            this.events = Object.assign({}, this.events || {}, extraEvents);
         }
     },
 });
diff --git a/addons/website/static/src/js/content/website_root.js b/addons/website/static/src/js/content/website_root.js
index 2190d838e34..f51d5932200 100644
--- a/addons/website/static/src/js/content/website_root.js
+++ b/addons/website/static/src/js/content/website_root.js
@@ -10,12 +10,12 @@ import "web.zoomodoo";
 
 export const WebsiteRoot = publicRootData.PublicRoot.extend(KeyboardNavigationMixin, {
     // TODO remove KeyboardNavigationMixin in master
-    events: _.extend({}, KeyboardNavigationMixin.events, publicRootData.PublicRoot.prototype.events || {}, {
+    events: Object.assign({}, KeyboardNavigationMixin.events, publicRootData.PublicRoot.prototype.events || {}, {
         'click .js_change_lang': '_onLangChangeClick',
         'click .js_publish_management .js_publish_btn': '_onPublishBtnClick',
         'shown.bs.modal': '_onModalShown',
     }),
-    custom_events: _.extend({}, publicRootData.PublicRoot.prototype.custom_events || {}, {
+    custom_events: Object.assign({}, publicRootData.PublicRoot.prototype.custom_events || {}, {
         'gmap_api_request': '_onGMapAPIRequest',
         'gmap_api_key_request': '_onGMapAPIKeyRequest',
         'ready_to_clean_for_save': '_onWidgetsStopRequest',
@@ -62,7 +62,7 @@ export const WebsiteRoot = publicRootData.PublicRoot.extend(KeyboardNavigationMi
      */
     _getContext: function (context) {
         var html = document.documentElement;
-        return _.extend({
+        return Object.assign({
             'website_id': html.getAttribute('data-website-id') | 0,
         }, this._super.apply(this, arguments));
     },
@@ -71,7 +71,7 @@ export const WebsiteRoot = publicRootData.PublicRoot.extend(KeyboardNavigationMi
      */
     _getExtraContext: function (context) {
         var html = document.documentElement;
-        return _.extend({
+        return Object.assign({
             'editable': !!(html.dataset.editable || $('[data-oe-model]').length), // temporary hack, this should be done in python
             'translatable': !!html.dataset.translatable,
             'edit_translations': !!html.dataset.edit_translations,
diff --git a/addons/website/static/src/js/editor/snippets.editor.js b/addons/website/static/src/js/editor/snippets.editor.js
index 862a2a6543b..2096557c49b 100644
--- a/addons/website/static/src/js/editor/snippets.editor.js
+++ b/addons/website/static/src/js/editor/snippets.editor.js
@@ -11,7 +11,7 @@ const getTraversedNodes = OdooEditorLib.getTraversedNodes;
 const FontFamilyPickerUserValueWidget = wSnippetOptions.FontFamilyPickerUserValueWidget;
 
 const wSnippetMenu = weSnippetEditor.SnippetsMenu.extend({
-    events: _.extend({}, weSnippetEditor.SnippetsMenu.prototype.events, {
+    events: Object.assign({}, weSnippetEditor.SnippetsMenu.prototype.events, {
         'click .o_we_customize_theme_btn': '_onThemeTabClick',
         'click .o_we_animate_text': '_onAnimateTextClick',
         'click .o_we_highlight_animated_text': '_onHighlightAnimatedTextClick',
@@ -21,7 +21,7 @@ const wSnippetMenu = weSnippetEditor.SnippetsMenu.extend({
         'gmap_api_key_request': '_onGMapAPIKeyRequest',
         'reload_bundles': '_onReloadBundles',
     }),
-    tabs: _.extend({}, weSnippetEditor.SnippetsMenu.prototype.tabs, {
+    tabs: Object.assign({}, weSnippetEditor.SnippetsMenu.prototype.tabs, {
         THEME: 'theme',
     }),
     optionsTabStructure: [
diff --git a/addons/website/static/src/js/editor/snippets.options.js b/addons/website/static/src/js/editor/snippets.options.js
index 51d82d7697c..6ae2e5b0307 100644
--- a/addons/website/static/src/js/editor/snippets.options.js
+++ b/addons/website/static/src/js/editor/snippets.options.js
@@ -39,10 +39,10 @@ options.UserValueWidget.include({
 });
 
 const UrlPickerUserValueWidget = InputUserValueWidget.extend({
-    custom_events: _.extend({}, InputUserValueWidget.prototype.custom_events || {}, {
+    custom_events: Object.assign({}, InputUserValueWidget.prototype.custom_events || {}, {
         'website_url_chosen': '_onWebsiteURLChosen',
     }),
-    events: _.extend({}, InputUserValueWidget.prototype.events || {}, {
+    events: Object.assign({}, InputUserValueWidget.prototype.events || {}, {
         'click .o_we_redirect_to': '_onRedirectTo',
     }),
 
@@ -99,7 +99,7 @@ const UrlPickerUserValueWidget = InputUserValueWidget.extend({
 });
 
 const FontFamilyPickerUserValueWidget = SelectUserValueWidget.extend({
-    events: _.extend({}, SelectUserValueWidget.prototype.events || {}, {
+    events: Object.assign({}, SelectUserValueWidget.prototype.events || {}, {
         'click .o_we_add_google_font_btn': '_onAddGoogleFontClick',
         'click .o_we_delete_google_font_btn': '_onDeleteGoogleFontClick',
     }),
@@ -540,7 +540,7 @@ options.userValueWidgetsRegistry['we-gpspicker'] = GPSPicker;
 //::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
 
 options.Class.include({
-    custom_events: _.extend({}, options.Class.prototype.custom_events || {}, {
+    custom_events: Object.assign({}, options.Class.prototype.custom_events || {}, {
         'google_fonts_custo_request': '_onGoogleFontsCustoRequest',
     }),
     specialCheckAndReloadMethodsNames: ['customizeWebsiteViews', 'customizeWebsiteVariable', 'customizeWebsiteColor'],
diff --git a/addons/website/static/src/js/editor/widget_link.js b/addons/website/static/src/js/editor/widget_link.js
index 2478cd524f3..5ef1c818360 100644
--- a/addons/website/static/src/js/editor/widget_link.js
+++ b/addons/website/static/src/js/editor/widget_link.js
@@ -4,7 +4,7 @@ import weWidgets from "wysiwyg.widgets";
 import wUtils from "website.utils";
 
 weWidgets.LinkTools.include({
-    custom_events: _.extend({}, weWidgets.LinkTools.prototype.custom_events || {}, {
+    custom_events: Object.assign({}, weWidgets.LinkTools.prototype.custom_events || {}, {
         website_url_chosen: '_onAutocompleteClose',
     }),
     LINK_DEBOUNCE: 1000,
diff --git a/addons/website/static/src/js/utils.js b/addons/website/static/src/js/utils.js
index 7238c6e8bfe..5e5189bd78b 100644
--- a/addons/website/static/src/js/utils.js
+++ b/addons/website/static/src/js/utils.js
@@ -177,7 +177,7 @@ function prompt(options, _qweb) {
     if (_.isUndefined(_qweb)) {
         _qweb = 'website.prompt';
     }
-    options = _.extend({
+    options = Object.assign({
         window_title: '',
         field_name: '',
         'default': '', // dict notation for IE<9
diff --git a/addons/website/static/src/js/widgets/link_popover_widget.js b/addons/website/static/src/js/widgets/link_popover_widget.js
index 5866f6b6906..2d55c804b4f 100644
--- a/addons/website/static/src/js/widgets/link_popover_widget.js
+++ b/addons/website/static/src/js/widgets/link_popover_widget.js
@@ -22,7 +22,7 @@ weWidgets.LinkPopoverWidget.include({
 });
 
 const NavbarLinkPopoverWidget = weWidgets.LinkPopoverWidget.extend({
-    events: _.extend({}, weWidgets.LinkPopoverWidget.prototype.events, {
+    events: Object.assign({}, weWidgets.LinkPopoverWidget.prototype.events, {
         'click .js_edit_menu': '_onEditMenuClick',
     }),
     /**
diff --git a/addons/website/static/src/snippets/s_chart/options.js b/addons/website/static/src/snippets/s_chart/options.js
index eccae79ec60..72f1855e14e 100644
--- a/addons/website/static/src/snippets/s_chart/options.js
+++ b/addons/website/static/src/snippets/s_chart/options.js
@@ -8,10 +8,10 @@ import weUtils from "web_editor.utils";
 var _t = core._t;
 
 options.registry.InnerChart = options.Class.extend({
-    custom_events: _.extend({}, options.Class.prototype.custom_events, {
+    custom_events: Object.assign({}, options.Class.prototype.custom_events, {
         'get_custom_colors': '_onGetCustomColors',
     }),
-    events: _.extend({}, options.Class.prototype.events, {
+    events: Object.assign({}, options.Class.prototype.events, {
         'click we-button.add_column': '_onAddColumnClick',
         'click we-button.add_row': '_onAddRowClick',
         'click we-button.o_we_matrix_remove_col': '_onRemoveColumnClick',
diff --git a/addons/website/static/src/snippets/s_countdown/options.js b/addons/website/static/src/snippets/s_countdown/options.js
index 4938e0b381c..541f98b5279 100644
--- a/addons/website/static/src/snippets/s_countdown/options.js
+++ b/addons/website/static/src/snippets/s_countdown/options.js
@@ -6,7 +6,7 @@ import options from "web_editor.snippets.options";
 const qweb = core.qweb;
 
 options.registry.countdown = options.Class.extend({
-    events: _.extend({}, options.Class.prototype.events || {}, {
+    events: Object.assign({}, options.Class.prototype.events || {}, {
         'click .toggle-edit-message': '_onToggleEndMessageClick',
     }),
 
diff --git a/addons/website/static/src/snippets/s_image_gallery/options.js b/addons/website/static/src/snippets/s_image_gallery/options.js
index 7a5c52cf5d3..3e3f1c90c70 100644
--- a/addons/website/static/src/snippets/s_image_gallery/options.js
+++ b/addons/website/static/src/snippets/s_image_gallery/options.js
@@ -92,7 +92,7 @@ options.registry.gallery = options.Class.extend({
     addImages: function (previewMode) {
         const $images = this.$('img');
         var $container = this.$('> .container, > .container-fluid, > .o_container_small');
-        const lastImage = _.last(this._getImages());
+        const lastImage = this._getImages().at(-1);
         let index = lastImage ? this._getIndex(lastImage) : -1;
         const dialog = new ComponentWrapper(this, MediaDialogWrapper, {
             multiImages: true,
diff --git a/addons/website/static/src/snippets/s_website_form/options.js b/addons/website/static/src/snippets/s_website_form/options.js
index 5f41e56ceba..9b99f2d9f36 100644
--- a/addons/website/static/src/snippets/s_website_form/options.js
+++ b/addons/website/static/src/snippets/s_website_form/options.js
@@ -284,7 +284,7 @@ const FieldEditor = FormEditor.extend({
 });
 
 options.registry.WebsiteFormEditor = FormEditor.extend({
-    events: _.extend({}, options.Class.prototype.events || {}, {
+    events: Object.assign({}, options.Class.prototype.events || {}, {
         'click .toggle-edit-message': '_onToggleEndMessageClick',
     }),
 
diff --git a/addons/website_crm_partner_assign/static/src/js/crm_partner_assign.js b/addons/website_crm_partner_assign/static/src/js/crm_partner_assign.js
index 6c700bda087..ac2b6660306 100644
--- a/addons/website_crm_partner_assign/static/src/js/crm_partner_assign.js
+++ b/addons/website_crm_partner_assign/static/src/js/crm_partner_assign.js
@@ -82,7 +82,7 @@ publicWidget.registry.crmPartnerAssign = publicWidget.Widget.extend({
             args: [[leadID], {
                 stage_id: stageID,
             }],
-            context: _.extend({website_partner_assign: 1}),
+            context: Object.assign({website_partner_assign: 1}),
         }).then(function () {
             window.location.reload();
         });
diff --git a/addons/website_event_exhibitor/static/src/js/event_exhibitor_connect.js b/addons/website_event_exhibitor/static/src/js/event_exhibitor_connect.js
index e651311654d..519981ae31d 100644
--- a/addons/website_event_exhibitor/static/src/js/event_exhibitor_connect.js
+++ b/addons/website_event_exhibitor/static/src/js/event_exhibitor_connect.js
@@ -5,7 +5,7 @@ import publicWidget from "web.public.widget";
 import {Markup} from "web.utils";
 
 var ExhibitorConnectClosedDialog = Dialog.extend({
-    events: _.extend({}, Dialog.prototype.events, {
+    events: Object.assign({}, Dialog.prototype.events, {
         'click .o_wesponsor_js_connect_modal_contry': '_onClickCountryFlag',
     }),
     template: 'exhibitor.connect.closed.modal',
diff --git a/addons/website_event_track_live/static/src/js/website_event_track_live.js b/addons/website_event_track_live/static/src/js/website_event_track_live.js
index 808b3d86cb1..d44eaa25395 100644
--- a/addons/website_event_track_live/static/src/js/website_event_track_live.js
+++ b/addons/website_event_track_live/static/src/js/website_event_track_live.js
@@ -7,7 +7,7 @@ import ReplaySuggestionWidget from "website_event_track_live.website_event_track
 
 publicWidget.registry.websiteEventTrackLive = publicWidget.Widget.extend({
     selector: '.o_wevent_event_track_live',
-    custom_events: _.extend({}, publicWidget.Widget.prototype.custom_events, {
+    custom_events: Object.assign({}, publicWidget.Widget.prototype.custom_events, {
         'video-ended': '_onVideoEnded'
     }),
 
diff --git a/addons/website_event_track_live_quiz/static/src/js/website_event_track_suggestion.js b/addons/website_event_track_live_quiz/static/src/js/website_event_track_suggestion.js
index 980cf3e7fc7..a5f32c4babf 100644
--- a/addons/website_event_track_live_quiz/static/src/js/website_event_track_suggestion.js
+++ b/addons/website_event_track_live_quiz/static/src/js/website_event_track_suggestion.js
@@ -3,7 +3,7 @@
 import WebsiteEventTrackSuggestion from "website_event_track_live.website_event_track_suggestion";
 
 var WebsiteEventTrackSuggestionLiveQuiz = WebsiteEventTrackSuggestion.include({
-    events: _.extend({}, WebsiteEventTrackSuggestion.prototype.events, {
+    events: Object.assign({}, WebsiteEventTrackSuggestion.prototype.events, {
         'click .owevent_track_suggestion_quiz': '_onQuizClick'
     }),
 
diff --git a/addons/website_event_track_quiz/static/src/js/event_quiz.js b/addons/website_event_track_quiz/static/src/js/event_quiz.js
index 9aba022c45b..53d9bc8c819 100644
--- a/addons/website_event_track_quiz/static/src/js/event_quiz.js
+++ b/addons/website_event_track_quiz/static/src/js/event_quiz.js
@@ -224,7 +224,7 @@ var Quiz = publicWidget.Widget.extend({
             if (data.error) {
                 self._alertShow(data.error);
             } else {
-                self.quiz = _.extend(self.quiz, data);
+                self.quiz = Object.assign(self.quiz, data);
                 self.quiz.quizPointsGained = data.quiz_points;
                 if (data.quiz_completed) {
                     self._disableAnswers();
diff --git a/addons/website_links/static/src/js/website_links.js b/addons/website_links/static/src/js/website_links.js
index 4ba6f592333..8b83635bf32 100644
--- a/addons/website_links/static/src/js/website_links.js
+++ b/addons/website_links/static/src/js/website_links.js
@@ -70,9 +70,7 @@ var SelectBox = publicWidget.Widget.extend({
      * @param {String} query
      */
     _objectExists: function (query) {
-        return _.find(this.objects, function (val) {
-            return val.text.toLowerCase() === query.toLowerCase();
-        }) !== undefined;
+        return this.objects.find(val => val.text.toLowerCase() === query.toLowerCase()) !== undefined;
     },
     /**
      * @private
diff --git a/addons/website_payment/static/src/js/website_payment_form.js b/addons/website_payment/static/src/js/website_payment_form.js
index 18f129aad78..599fe99e896 100644
--- a/addons/website_payment/static/src/js/website_payment_form.js
+++ b/addons/website_payment/static/src/js/website_payment_form.js
@@ -4,7 +4,7 @@ import core, { _t } from 'web.core';
 import checkoutForm from 'payment.checkout_form';
 
 checkoutForm.include({
-    events: _.extend({}, checkoutForm.prototype.events || {}, {
+    events: Object.assign({}, checkoutForm.prototype.events || {}, {
         'change .o_wpayment_fee_impact': '_onFeeParameterChange',
     }),
 
diff --git a/addons/website_sale/static/src/js/website_sale.editor.js b/addons/website_sale/static/src/js/website_sale.editor.js
index d4e0e77db08..d16ef7ada6c 100644
--- a/addons/website_sale/static/src/js/website_sale.editor.js
+++ b/addons/website_sale/static/src/js/website_sale.editor.js
@@ -304,7 +304,7 @@ options.registry.WebsiteSaleGridLayout = options.Class.extend({
 });
 
 options.registry.WebsiteSaleProductsItem = options.Class.extend({
-    events: _.extend({}, options.Class.prototype.events || {}, {
+    events: Object.assign({}, options.Class.prototype.events || {}, {
         'mouseenter .o_wsale_soptions_menu_sizes table': '_onTableMouseEnter',
         'mouseleave .o_wsale_soptions_menu_sizes table': '_onTableMouseLeave',
         'mouseover .o_wsale_soptions_menu_sizes td': '_onTableItemMouseEnter',
diff --git a/addons/website_sale/static/src/js/website_sale.js b/addons/website_sale/static/src/js/website_sale.js
index eb5eae1b5fa..9ca64ade91f 100644
--- a/addons/website_sale/static/src/js/website_sale.js
+++ b/addons/website_sale/static/src/js/website_sale.js
@@ -15,7 +15,7 @@ import { ProductImageViewerWrapper } from "@website_sale/js/components/website_s
 
 publicWidget.registry.WebsiteSale = publicWidget.Widget.extend(VariantMixin, cartHandlerMixin, {
     selector: '.oe_website_sale',
-    events: _.extend({}, VariantMixin.events || {}, {
+    events: Object.assign({}, VariantMixin.events || {}, {
         'change form .js_product:first input[name="add_qty"]': '_onChangeAddQuantity',
         'mouseup .js_publish': '_onMouseupPublish',
         'touchend .js_publish': '_onMouseupPublish',
diff --git a/addons/website_sale/static/src/snippets/s_add_to_cart/options.js b/addons/website_sale/static/src/snippets/s_add_to_cart/options.js
index df241ebdd85..a65993dff89 100644
--- a/addons/website_sale/static/src/snippets/s_add_to_cart/options.js
+++ b/addons/website_sale/static/src/snippets/s_add_to_cart/options.js
@@ -25,7 +25,7 @@ const Many2oneDefaultMessageWidget = Many2oneUserValueWidget.extend({
 options.userValueWidgetsRegistry['we-many2one-default-message'] = Many2oneDefaultMessageWidget;
 
 options.registry.AddToCart = options.Class.extend({
-    events: _.extend({}, options.Class.prototype.events || {}, {
+    events: Object.assign({}, options.Class.prototype.events || {}, {
         'click .reset-variant-picker': '_onClickResetVariantPicker',
         'click .reset-product-picker': '_onClickResetProductPicker',
     }),
diff --git a/addons/website_sale_comparison_wishlist/static/src/js/wishlist.js b/addons/website_sale_comparison_wishlist/static/src/js/wishlist.js
index e9155c93473..1bedc2eafb6 100644
--- a/addons/website_sale_comparison_wishlist/static/src/js/wishlist.js
+++ b/addons/website_sale_comparison_wishlist/static/src/js/wishlist.js
@@ -4,7 +4,7 @@ import publicWidget from 'web.public.widget';
 import 'website_sale_comparison.comparison';
 
 publicWidget.registry.ProductComparison.include({
-    events: _.extend({}, publicWidget.registry.ProductComparison.prototype.events, {
+    events: Object.assign({}, publicWidget.registry.ProductComparison.prototype.events, {
         'click .wishlist-section .o_add_to_compare': '_onClickCompare',
     }),
 
diff --git a/addons/website_sale_mondialrelay/static/src/js/website_sale_mondialrelay.js b/addons/website_sale_mondialrelay/static/src/js/website_sale_mondialrelay.js
index ba33316a9d6..669898bb8cc 100644
--- a/addons/website_sale_mondialrelay/static/src/js/website_sale_mondialrelay.js
+++ b/addons/website_sale_mondialrelay/static/src/js/website_sale_mondialrelay.js
@@ -18,7 +18,7 @@ function corsIgnoredErrorHandler(env, error) {
 }
 
 WebsiteSaleDeliveryWidget.include({
-    events: _.extend({
+    events: Object.assign({
         "click #btn_confirm_relay": "_onClickBtnConfirmRelay",
     }, WebsiteSaleDeliveryWidget.prototype.events),
 
diff --git a/addons/website_sale_slides/static/src/js/slides_course_quiz.js b/addons/website_sale_slides/static/src/js/slides_course_quiz.js
index 0ef9e58f000..0b0a4fd7e45 100644
--- a/addons/website_sale_slides/static/src/js/slides_course_quiz.js
+++ b/addons/website_sale_slides/static/src/js/slides_course_quiz.js
@@ -4,7 +4,7 @@ import {websiteSlidesQuizNoFullscreen} from "@website_slides/js/slides_course_qu
 
 websiteSlidesQuizNoFullscreen.include({
     _extractChannelData: function (slideData) {
-        return _.extend({}, this._super.apply(this, arguments), {
+        return Object.assign({}, this._super.apply(this, arguments), {
             productId: slideData.productId,
             enroll: slideData.enroll,
             currencyName: slideData.currencyName,
diff --git a/addons/website_slides/static/src/js/slides_course_fullscreen_player.js b/addons/website_slides/static/src/js/slides_course_fullscreen_player.js
index 708b52e5613..ea6eb50ebdf 100644
--- a/addons/website_slides/static/src/js/slides_course_fullscreen_player.js
+++ b/addons/website_slides/static/src/js/slides_course_fullscreen_player.js
@@ -22,7 +22,7 @@
      */
     var findSlide = function (slideList, matcher) {
         var slideMatch = _.matcher(matcher);
-        return _.find(slideList, slideMatch);
+        return slideList.find(slide => slideMatch(slide));
     };
 
     /**
@@ -494,10 +494,10 @@
      * This widget is rendered sever side, and attached to the existing DOM.
      */
     var Fullscreen = SlideCoursePage.extend({
-        events: _.extend({}, SlideCoursePage.prototype.events, {
+        events: Object.assign({}, SlideCoursePage.prototype.events, {
             'click .o_wslides_fs_toggle_sidebar': '_onClickToggleSidebar',
         }),
-        custom_events: _.extend({}, SlideCoursePage.prototype.custom_events, {
+        custom_events: Object.assign({}, SlideCoursePage.prototype.custom_events, {
             'change_slide': '_onChangeSlideRequest',
             'slide_go_next': '_onSlideGoToNext',
         }),
diff --git a/addons/website_slides/static/src/js/slides_course_quiz.js b/addons/website_slides/static/src/js/slides_course_quiz.js
index dc879bad900..8b7f8a1291a 100644
--- a/addons/website_slides/static/src/js/slides_course_quiz.js
+++ b/addons/website_slides/static/src/js/slides_course_quiz.js
@@ -690,7 +690,7 @@
 
     publicWidget.registry.websiteSlidesQuizNoFullscreen = SlideCoursePage.extend({
         selector: '.o_wslides_lesson_main', // selector of complete page, as we need slide content and aside content table
-        custom_events: _.extend({}, SlideCoursePage.prototype.custom_events, {
+        custom_events: Object.assign({}, SlideCoursePage.prototype.custom_events, {
             slide_go_next: '_onQuizNextSlide',
         }),
 
diff --git a/addons/website_slides/static/src/js/slides_course_tag_add.js b/addons/website_slides/static/src/js/slides_course_tag_add.js
index fa1df40f810..29d69576db8 100644
--- a/addons/website_slides/static/src/js/slides_course_tag_add.js
+++ b/addons/website_slides/static/src/js/slides_course_tag_add.js
@@ -6,7 +6,7 @@ import publicWidget from 'web.public.widget';
 
 var TagCourseDialog = Dialog.extend({
     template: 'website.slides.tag.add',
-    events: _.extend({}, Dialog.prototype.events, {
+    events: Object.assign({}, Dialog.prototype.events, {
         'change input#tag_id' : '_onChangeTag',
     }),
 
diff --git a/addons/website_slides/static/src/js/slides_upload.js b/addons/website_slides/static/src/js/slides_upload.js
index 88c5cce28d9..7ff32dc4680 100644
--- a/addons/website_slides/static/src/js/slides_upload.js
+++ b/addons/website_slides/static/src/js/slides_upload.js
@@ -8,7 +8,7 @@ import wUtils from 'website.utils';
 
 var SlideUploadDialog = Dialog.extend({
     template: 'website.slide.upload.modal',
-    events: _.extend({}, Dialog.prototype.events, {
+    events: Object.assign({}, Dialog.prototype.events, {
         'click .o_wslides_js_upload_install_button': '_onClickInstallModule',
         'click .o_wslides_select_category': '_onClickSlideCategoryIcon',
         'change input#upload': '_onChangeSlideUpload',
@@ -156,7 +156,7 @@ var SlideUploadDialog = Dialog.extend({
         } else {
             sourceType = this.$('input[name="source_type"]:checked').data('value');
         }
-        var values = _.extend({
+        var values = Object.assign({
             'channel_id': this.channelID,
             'description': this._formGetFieldValue('description'),
             'document_google_url': this._formGetFieldValue('document_google_url'),
@@ -171,17 +171,17 @@ var SlideUploadDialog = Dialog.extend({
 
         var canvas = this.$('#data_canvas')[0];
         if (this.file.type === 'application/pdf') {
-            _.extend(values, {
+            Object.assign(values, {
                 'image_1920': canvas.toDataURL().split(',')[1],
                 'slide_category': 'document',
                 'binary_content': this.file.data
             });
         } else if (values['slide_category'] === 'article') {
-            _.extend(values, {
+            Object.assign(values, {
                 'image_1920': this.file.type === 'image/svg+xml' ? await this._svgToPng() : this.file.data,
             });
         } else if (/^image\/.*/.test(this.file.type)) {
-            _.extend(values, {
+            Object.assign(values, {
                 'slide_category': 'infographic',
                 'binary_content': this.file.type === 'image/svg+xml' ? await this._svgToPNG() : this.file.data,
             });
@@ -656,7 +656,7 @@ var SlideUploadDialog = Dialog.extend({
                     .text(_.str.sprintf(_t('Failed to install "%s".'), this.modulesToInstallStatus.name));
             }
         } else {
-            this.modulesToInstallStatus = _.extend({}, _.find(this.modulesToInstall, function (item) { return item.id === moduleId; }));
+            this.modulesToInstallStatus = Object.assign({}, this.modulesToInstall.find( function (item) { return item.id === moduleId; }));
             this.set('state', '_import');
             this.$('#o_wslides_install_module_text')
                 .text(_.str.sprintf(_t('Do you want to install the "%s" app?'), this.modulesToInstallStatus.name));
diff --git a/addons/website_slides_survey/static/src/js/slides_upload.js b/addons/website_slides_survey/static/src/js/slides_upload.js
index 797794f3765..5afc3363288 100644
--- a/addons/website_slides_survey/static/src/js/slides_upload.js
+++ b/addons/website_slides_survey/static/src/js/slides_upload.js
@@ -8,7 +8,7 @@ import SlidesUpload from "@website_slides/js/slides_upload";
  * Management of the new 'certification' slide_category
  */
 SlidesUpload.SlideUploadDialog.include({
-    events: _.extend({}, SlidesUpload.SlideUploadDialog.prototype.events || {}, {
+    events: Object.assign({}, SlidesUpload.SlideUploadDialog.prototype.events || {}, {
         'change input#certification_id': '_onChangeCertification'
     }),