diff --git a/app/assets/javascripts/awards_handler.js b/app/assets/javascripts/awards_handler.js
index 18cd04b176a43b352473140d763688e5a10f1904..097f79a250aa7220cce66b7942a528fea88c0ba9 100644
--- a/app/assets/javascripts/awards_handler.js
+++ b/app/assets/javascripts/awards_handler.js
@@ -1,6 +1,6 @@
 /* eslint-disable class-methods-use-this */
 /* global Flash */
-
+import _ from 'underscore';
 import Cookies from 'js-cookie';
 
 const animationEndEventString = 'animationend webkitAnimationEnd MSAnimationEnd oAnimationEnd';
diff --git a/app/assets/javascripts/behaviors/requires_input.js b/app/assets/javascripts/behaviors/requires_input.js
index b20d108aa2580fd2139850be2ec611532928a45c..035a7e5c4313d95a0a7d660852a716d01a9a4cd2 100644
--- a/app/assets/javascripts/behaviors/requires_input.js
+++ b/app/assets/javascripts/behaviors/requires_input.js
@@ -1,3 +1,4 @@
+import _ from 'underscore';
 import '../commons/bootstrap';
 
 // Requires Input behavior
@@ -48,7 +49,9 @@ function hideOrShowHelpBlock(form) {
 
 $(() => {
   const $form = $('form.js-requires-input');
-  $form.requiresInput();
-  hideOrShowHelpBlock($form);
-  $('.select2.js-select-namespace').change(() => hideOrShowHelpBlock($form));
+  if ($form) {
+    $form.requiresInput();
+    hideOrShowHelpBlock($form);
+    $('.select2.js-select-namespace').change(() => hideOrShowHelpBlock($form));
+  }
 });
diff --git a/app/assets/javascripts/behaviors/toggler_behavior.js b/app/assets/javascripts/behaviors/toggler_behavior.js
index 77e92ff8caf9ddf4a520d33e89a8b6b968d011cb..b70b0a9bbf8465112d67b52652909227b9b609a8 100644
--- a/app/assets/javascripts/behaviors/toggler_behavior.js
+++ b/app/assets/javascripts/behaviors/toggler_behavior.js
@@ -1,4 +1,3 @@
-
 // Toggle button. Show/hide content inside parent container.
 // Button does not change visibility. If button has icon - it changes chevron style.
 //
diff --git a/app/assets/javascripts/boards/boards_bundle.js b/app/assets/javascripts/boards/boards_bundle.js
index 88b054b76e660f6cca79fdf30b9637c4de63756e..89c1418014988bcb360aef6cff2b4b7888e4ce1a 100644
--- a/app/assets/javascripts/boards/boards_bundle.js
+++ b/app/assets/javascripts/boards/boards_bundle.js
@@ -2,6 +2,7 @@
 /* global BoardService */
 /* global Flash */
 
+import _ from 'underscore';
 import Vue from 'vue';
 import VueResource from 'vue-resource';
 import FilteredSearchBoards from './filtered_search_boards';
diff --git a/app/assets/javascripts/boards/components/board_blank_state.js b/app/assets/javascripts/boards/components/board_blank_state.js
index e7f16899362b4f2771291932655f82a1ab4a7ae7..edfe7c326dbd77e1f4d4318de6554cf94a82ac64 100644
--- a/app/assets/javascripts/boards/components/board_blank_state.js
+++ b/app/assets/javascripts/boards/components/board_blank_state.js
@@ -1,5 +1,6 @@
 /* global ListLabel */
 
+import _ from 'underscore';
 import Cookies from 'js-cookie';
 
 const Store = gl.issueBoards.BoardsStore;
diff --git a/app/assets/javascripts/boards/components/new_list_dropdown.js b/app/assets/javascripts/boards/components/new_list_dropdown.js
index f29b6caa1acec7e0f3cfe9df5fa630f7fbcece2e..72bb9e10fbc7eadccd8969f343ff77e584b8e0ee 100644
--- a/app/assets/javascripts/boards/components/new_list_dropdown.js
+++ b/app/assets/javascripts/boards/components/new_list_dropdown.js
@@ -1,5 +1,6 @@
 /* eslint-disable comma-dangle, func-names, no-new, space-before-function-paren, one-var,
    promise/catch-or-return */
+import _ from 'underscore';
 
 window.gl = window.gl || {};
 window.gl.issueBoards = window.gl.issueBoards || {};
diff --git a/app/assets/javascripts/boards/stores/boards_store.js b/app/assets/javascripts/boards/stores/boards_store.js
index 1e12d4ca4154ed558970c78f9de0fc8f8ccfded7..43928e602d66f90f33ec43fc573104ae037743e7 100644
--- a/app/assets/javascripts/boards/stores/boards_store.js
+++ b/app/assets/javascripts/boards/stores/boards_store.js
@@ -1,6 +1,6 @@
 /* eslint-disable comma-dangle, space-before-function-paren, one-var, no-shadow, dot-notation, max-len */
 /* global List */
-
+import _ from 'underscore';
 import Cookies from 'js-cookie';
 
 window.gl = window.gl || {};
diff --git a/app/assets/javascripts/commons/index.js b/app/assets/javascripts/commons/index.js
index 7063f59d446abcdc52630c66aad3526905c3d678..6db8b3afbef8407d4af286dfe42ca1bce2a86730 100644
--- a/app/assets/javascripts/commons/index.js
+++ b/app/assets/javascripts/commons/index.js
@@ -1,3 +1,4 @@
+import 'underscore';
 import './polyfills';
 import './jquery';
 import './bootstrap';
diff --git a/app/assets/javascripts/copy_as_gfm.js b/app/assets/javascripts/copy_as_gfm.js
index 54257531284869c5bbd9f4af804d406bb78af2b5..13ba4a57293a093d03660ef956d7f5a09805a7a7 100644
--- a/app/assets/javascripts/copy_as_gfm.js
+++ b/app/assets/javascripts/copy_as_gfm.js
@@ -1,5 +1,5 @@
 /* eslint-disable class-methods-use-this, object-shorthand, no-unused-vars, no-use-before-define, no-new, max-len, no-restricted-syntax, guard-for-in, no-continue */
-
+import _ from 'underscore';
 import './lib/utils/common_utils';
 import { placeholderImage } from './lazy_loader';
 
diff --git a/app/assets/javascripts/dispatcher.js b/app/assets/javascripts/dispatcher.js
index 178e72a1127046bcad11cf9ca3dbc85c64cad457..070d0a01c0f5d9af899db683d484b853463b949e 100644
--- a/app/assets/javascripts/dispatcher.js
+++ b/app/assets/javascripts/dispatcher.js
@@ -79,10 +79,6 @@ import GpgBadges from './gpg_badges';
 (function() {
   var Dispatcher;
 
-  $(function() {
-    return new Dispatcher();
-  });
-
   Dispatcher = (function() {
     function Dispatcher() {
       this.initSearch();
@@ -637,4 +633,8 @@ import GpgBadges from './gpg_badges';
 
     return Dispatcher;
   })();
+
+  $(function() {
+    new Dispatcher();
+  });
 }).call(window);
diff --git a/app/assets/javascripts/dropzone_input.js b/app/assets/javascripts/dropzone_input.js
index 9ebbb22e8073b7eace427bec8b9aa808199c224b..bd1864b8321d02f480ca01c971f7e48ac247715f 100644
--- a/app/assets/javascripts/dropzone_input.js
+++ b/app/assets/javascripts/dropzone_input.js
@@ -1,11 +1,10 @@
 /* eslint-disable func-names, space-before-function-paren, wrap-iife, max-len, one-var, no-var, one-var-declaration-per-line, no-unused-vars, camelcase, quotes, no-useless-concat, prefer-template, quote-props, comma-dangle, object-shorthand, consistent-return, prefer-arrow-callback */
 /* global Dropzone */
-
+import _ from 'underscore';
 import './preview_markdown';
 
 window.DropzoneInput = (function() {
   function DropzoneInput(form) {
-    Dropzone.autoDiscover = false;
     const divHover = '<div class="div-dropzone-hover"></div>';
     const iconPaperclip = '<i class="fa fa-paperclip div-dropzone-icon"></i>';
     const $attachButton = form.find('.button-attach-file');
diff --git a/app/assets/javascripts/emoji/index.js b/app/assets/javascripts/emoji/index.js
index cac35d6eed5e2569b6f94cf69f4c7754b30dfebf..dc7672560eae564e4ffda179eb180f8eb1348599 100644
--- a/app/assets/javascripts/emoji/index.js
+++ b/app/assets/javascripts/emoji/index.js
@@ -1,3 +1,4 @@
+import _ from 'underscore';
 import emojiMap from 'emojis/digests.json';
 import emojiAliases from 'emojis/aliases.json';
 
diff --git a/app/assets/javascripts/filterable_list.js b/app/assets/javascripts/filterable_list.js
index 139206cc1855c2b76a80560eb833b8ad61b13123..6d516a253bb6e7865c600ad5a610ab286729dd92 100644
--- a/app/assets/javascripts/filterable_list.js
+++ b/app/assets/javascripts/filterable_list.js
@@ -1,3 +1,5 @@
+import _ from 'underscore';
+
 /**
  * Makes search request for content when user types a value in the search input.
  * Updates the html content of the page with the received one.
diff --git a/app/assets/javascripts/filtered_search/dropdown_utils.js b/app/assets/javascripts/filtered_search/dropdown_utils.js
index 9c7a4d9f6ad9c4479b73dbae1e588ffecdf70ce4..db5560fa7535d9177687ac0d4540e114aa2fcbbd 100644
--- a/app/assets/javascripts/filtered_search/dropdown_utils.js
+++ b/app/assets/javascripts/filtered_search/dropdown_utils.js
@@ -1,3 +1,4 @@
+import _ from 'underscore';
 import FilteredSearchContainer from './container';
 
 class DropdownUtils {
diff --git a/app/assets/javascripts/gfm_auto_complete.js b/app/assets/javascripts/gfm_auto_complete.js
index 6cb9cfe138248220110088d81ce78b369c4d44d5..5c624b79d456337f034552042015fef2b758e448 100644
--- a/app/assets/javascripts/gfm_auto_complete.js
+++ b/app/assets/javascripts/gfm_auto_complete.js
@@ -1,3 +1,4 @@
+import _ from 'underscore';
 import glRegexp from './lib/utils/regexp';
 import AjaxCache from './lib/utils/ajax_cache';
 
diff --git a/app/assets/javascripts/gl_dropdown.js b/app/assets/javascripts/gl_dropdown.js
index 9475498e17659cdb733566d8f881ca7594ffea09..a17680794cc39c7859fb4666da33b583bd383c57 100644
--- a/app/assets/javascripts/gl_dropdown.js
+++ b/app/assets/javascripts/gl_dropdown.js
@@ -1,5 +1,6 @@
 /* eslint-disable func-names, space-before-function-paren, no-var, one-var, one-var-declaration-per-line, prefer-rest-params, max-len, vars-on-top, wrap-iife, no-unused-vars, quotes, no-shadow, no-cond-assign, prefer-arrow-callback, no-return-assign, no-else-return, camelcase, comma-dangle, no-lonely-if, guard-for-in, no-restricted-syntax, consistent-return, prefer-template, no-param-reassign, no-loop-func, no-mixed-operators */
 /* global fuzzaldrinPlus */
+import _ from 'underscore';
 import { isObject } from './lib/utils/type_utility';
 
 var GitLabDropdown, GitLabDropdownFilter, GitLabDropdownRemote;
diff --git a/app/assets/javascripts/graphs/stat_graph_contributors.js b/app/assets/javascripts/graphs/stat_graph_contributors.js
index c6be4c9e8feb184d93a69229a18cf350e2efe539..cdc4fcf65738faa3470bb063403f19c26c822328 100644
--- a/app/assets/javascripts/graphs/stat_graph_contributors.js
+++ b/app/assets/javascripts/graphs/stat_graph_contributors.js
@@ -1,5 +1,6 @@
 /* eslint-disable func-names, space-before-function-paren, wrap-iife, no-var, one-var, camelcase, one-var-declaration-per-line, quotes, no-param-reassign, quote-props, comma-dangle, prefer-template, max-len, no-return-assign, no-shadow */
 
+import _ from 'underscore';
 import d3 from 'd3';
 import { ContributorsGraph, ContributorsAuthorGraph, ContributorsMasterGraph } from './stat_graph_contributors_graph';
 import ContributorsStatGraphUtil from './stat_graph_contributors_util';
diff --git a/app/assets/javascripts/graphs/stat_graph_contributors_graph.js b/app/assets/javascripts/graphs/stat_graph_contributors_graph.js
index 0deb27e522b4a5cdb98db71095c6d589fded24ac..f64b4638485f11dfa098418c2ebf4ade0b55d05c 100644
--- a/app/assets/javascripts/graphs/stat_graph_contributors_graph.js
+++ b/app/assets/javascripts/graphs/stat_graph_contributors_graph.js
@@ -1,5 +1,5 @@
 /* eslint-disable func-names, space-before-function-paren, no-var, prefer-rest-params, max-len, no-restricted-syntax, vars-on-top, no-use-before-define, no-param-reassign, new-cap, no-underscore-dangle, wrap-iife, comma-dangle, no-return-assign, prefer-arrow-callback, quotes, prefer-template, newline-per-chained-call, no-else-return, no-shadow */
-
+import _ from 'underscore';
 import d3 from 'd3';
 
 const extend = function(child, parent) { for (var key in parent) { if (hasProp.call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = child; } ctor.prototype = parent.prototype; child.prototype = new ctor(); child.__super__ = parent.prototype; return child; };
diff --git a/app/assets/javascripts/graphs/stat_graph_contributors_util.js b/app/assets/javascripts/graphs/stat_graph_contributors_util.js
index c583757f3f2f44daa588a7ae33a481b867c1e761..77135ad1f0e3ce1258774cfa07361c247637d88a 100644
--- a/app/assets/javascripts/graphs/stat_graph_contributors_util.js
+++ b/app/assets/javascripts/graphs/stat_graph_contributors_util.js
@@ -1,4 +1,5 @@
 /* eslint-disable func-names, space-before-function-paren, object-shorthand, no-var, one-var, camelcase, one-var-declaration-per-line, comma-dangle, no-param-reassign, no-return-assign, quotes, prefer-arrow-callback, wrap-iife, consistent-return, no-unused-vars, max-len, no-cond-assign, no-else-return, max-len */
+import _ from 'underscore';
 
 export default {
   parse_log: function(log) {
diff --git a/app/assets/javascripts/issuable_bulk_update_actions.js b/app/assets/javascripts/issuable_bulk_update_actions.js
index e46c0e902555700fdfb7a49c3ae81d859427d322..c39ffdb2e0fd4ed318d3a8630b799974fdea490d 100644
--- a/app/assets/javascripts/issuable_bulk_update_actions.js
+++ b/app/assets/javascripts/issuable_bulk_update_actions.js
@@ -1,6 +1,7 @@
 /* eslint-disable comma-dangle, quotes, consistent-return, func-names, array-callback-return, space-before-function-paren, prefer-arrow-callback, max-len, no-unused-expressions, no-sequences, no-underscore-dangle, no-unused-vars, no-param-reassign */
 /* global IssuableIndex */
 /* global Flash */
+import _ from 'underscore';
 
 export default {
   init({ container, form, issues, prefixId } = {}) {
diff --git a/app/assets/javascripts/issuable_index.js b/app/assets/javascripts/issuable_index.js
index 5c96646def832680d24daa074b2621988588b4c7..ece0220c927ffa654c0ed6262f8ad4247a63ef84 100644
--- a/app/assets/javascripts/issuable_index.js
+++ b/app/assets/javascripts/issuable_index.js
@@ -1,6 +1,6 @@
 /* eslint-disable no-param-reassign, func-names, no-var, camelcase, no-unused-vars, object-shorthand, space-before-function-paren, no-return-assign, comma-dangle, consistent-return, one-var, one-var-declaration-per-line, quotes, prefer-template, prefer-arrow-callback, wrap-iife, max-len */
 /* global IssuableIndex */
-
+import _ from 'underscore';
 import IssuableBulkUpdateSidebar from './issuable_bulk_update_sidebar';
 import IssuableBulkUpdateActions from './issuable_bulk_update_actions';
 
diff --git a/app/assets/javascripts/labels_select.js b/app/assets/javascripts/labels_select.js
index f0e02ca0fb211c4a87f20b80403fe36526967a42..7d7f91227f99dbe040f1e0408dfce876bff90f08 100644
--- a/app/assets/javascripts/labels_select.js
+++ b/app/assets/javascripts/labels_select.js
@@ -1,7 +1,7 @@
 /* eslint-disable no-useless-return, func-names, space-before-function-paren, wrap-iife, no-var, no-underscore-dangle, prefer-arrow-callback, max-len, one-var, no-unused-vars, one-var-declaration-per-line, prefer-template, no-new, consistent-return, object-shorthand, comma-dangle, no-shadow, no-param-reassign, brace-style, vars-on-top, quotes, no-lonely-if, no-else-return, dot-notation, no-empty, no-return-assign, camelcase, prefer-spread */
 /* global Issuable */
 /* global ListLabel */
-
+import _ from 'underscore';
 import IssuableBulkUpdateActions from './issuable_bulk_update_actions';
 import DropdownUtils from './filtered_search/dropdown_utils';
 
diff --git a/app/assets/javascripts/lib/utils/pretty_time.js b/app/assets/javascripts/lib/utils/pretty_time.js
index ae397212e55f750deb701d35c184e3f2222c62f8..716aefbfcb70162c8c8c807f5d71deaa12ad620f 100644
--- a/app/assets/javascripts/lib/utils/pretty_time.js
+++ b/app/assets/javascripts/lib/utils/pretty_time.js
@@ -1,3 +1,5 @@
+import _ from 'underscore';
+
 (() => {
   /*
    * TODO: Make these methods more configurable (e.g. parseSeconds timePeriodContstraints,
diff --git a/app/assets/javascripts/main.js b/app/assets/javascripts/main.js
index cd45091c21146adef21ab2073bb3707fa6dd2d4d..a807ce326a6b05771765700412ea33de04397ef4 100644
--- a/app/assets/javascripts/main.js
+++ b/app/assets/javascripts/main.js
@@ -36,9 +36,6 @@ import './shortcuts_find_file';
 import './shortcuts_issuable';
 import './shortcuts_network';
 
-// behaviors
-import './behaviors/';
-
 // templates
 import './templates/issuable_template_selector';
 import './templates/issuable_template_selectors';
@@ -56,6 +53,9 @@ import './lib/utils/pretty_time';
 import './lib/utils/text_utility';
 import './lib/utils/url_utility';
 
+// behaviors
+import './behaviors/';
+
 // u2f
 import './u2f/authenticate';
 import './u2f/error';
@@ -86,7 +86,6 @@ import './copy_as_gfm';
 import './copy_to_clipboard';
 import './create_label';
 import './diff';
-import './dispatcher';
 import './dropzone_input';
 import './due_date_select';
 import './files_comment_button';
@@ -150,9 +149,13 @@ import './subscription';
 import './subscription_select';
 import './syntax_highlight';
 
+import './dispatcher';
+
 // eslint-disable-next-line global-require, import/no-commonjs
 if (process.env.NODE_ENV !== 'production') require('./test_utils/');
 
+Dropzone.autoDiscover = false;
+
 document.addEventListener('beforeunload', function () {
   // Unbind scroll events
   $(document).off('scroll');
diff --git a/app/assets/javascripts/milestone_select.js b/app/assets/javascripts/milestone_select.js
index 6756ab0b3aa43308ca083b575ff46376686443ec..045790586884d93fd8f9d1057ff05f7da8f92702 100644
--- a/app/assets/javascripts/milestone_select.js
+++ b/app/assets/javascripts/milestone_select.js
@@ -1,6 +1,7 @@
 /* eslint-disable func-names, space-before-function-paren, wrap-iife, no-var, no-underscore-dangle, prefer-arrow-callback, max-len, one-var, one-var-declaration-per-line, no-unused-vars, object-shorthand, comma-dangle, no-else-return, no-self-compare, consistent-return, no-param-reassign, no-shadow */
 /* global Issuable */
 /* global ListMilestone */
+import _ from 'underscore';
 
 (function() {
   this.MilestoneSelect = (function() {
diff --git a/app/assets/javascripts/notes.js b/app/assets/javascripts/notes.js
index dfa07a2def49beed1166c53718aae9c3b31239eb..b38a6abc8d1abdc69de73573f1d1c7ae6a568a7b 100644
--- a/app/assets/javascripts/notes.js
+++ b/app/assets/javascripts/notes.js
@@ -11,6 +11,7 @@ newline-per-chained-call, no-useless-escape, class-methods-use-this */
 /* global mrRefreshWidgetUrl */
 
 import $ from 'jquery';
+import _ from 'underscore';
 import Cookies from 'js-cookie';
 import autosize from 'vendor/autosize';
 import Dropzone from 'dropzone';
diff --git a/app/assets/javascripts/pipeline_schedules/components/interval_pattern_input.vue b/app/assets/javascripts/pipeline_schedules/components/interval_pattern_input.vue
index ce46b3fa3fada130bdb1bd62dfe1103ac03dee3f..b5d85299cf83dbe23b67d35d0d504a369c650e2b 100644
--- a/app/assets/javascripts/pipeline_schedules/components/interval_pattern_input.vue
+++ b/app/assets/javascripts/pipeline_schedules/components/interval_pattern_input.vue
@@ -1,4 +1,6 @@
 <script>
+  import _ from 'underscore';
+
   export default {
     props: {
       initialCronInterval: {
diff --git a/app/assets/javascripts/profile/gl_crop.js b/app/assets/javascripts/profile/gl_crop.js
index f32b24137257ca13de39a322c47a3a528884f973..291ae24aa68bdb7fba91ef8e6d204054369bac42 100644
--- a/app/assets/javascripts/profile/gl_crop.js
+++ b/app/assets/javascripts/profile/gl_crop.js
@@ -1,6 +1,7 @@
 /* eslint-disable no-useless-escape, max-len, quotes, no-var, no-underscore-dangle, func-names, space-before-function-paren, no-unused-vars, no-return-assign, object-shorthand, one-var, one-var-declaration-per-line, comma-dangle, consistent-return, class-methods-use-this, new-parens */
 
 import 'cropper';
+import _ from 'underscore';
 
 ((global) => {
   // Matches everything but the file name
diff --git a/app/assets/javascripts/project_edit.js b/app/assets/javascripts/project_edit.js
index d7d284b6c86ff132be1818c2c255c212b632e0fa..7572fec15e001a2fe02cd574a554de14ee28fc31 100644
--- a/app/assets/javascripts/project_edit.js
+++ b/app/assets/javascripts/project_edit.js
@@ -1,6 +1,6 @@
 export default function setupProjectEdit() {
   const $transferForm = $('.js-project-transfer-form');
-  const $selectNamespace = $transferForm.find('.select2');
+  const $selectNamespace = $transferForm.find('select.select2');
 
   $selectNamespace.on('change', () => {
     $transferForm.find(':submit').prop('disabled', !$selectNamespace.val());
diff --git a/app/assets/javascripts/protected_branches/protected_branch_dropdown.js b/app/assets/javascripts/protected_branches/protected_branch_dropdown.js
index cc0b2ebe0710f1f67e2c707f9928661ab21e1a2e..678882a8d2c63d51f3c02a5ea1e56fac7575ba92 100644
--- a/app/assets/javascripts/protected_branches/protected_branch_dropdown.js
+++ b/app/assets/javascripts/protected_branches/protected_branch_dropdown.js
@@ -1,3 +1,5 @@
+import _ from 'underscore';
+
 export default class ProtectedBranchDropdown {
   /**
    * @param {Object} options containing
diff --git a/app/assets/javascripts/protected_tags/protected_tag_dropdown.js b/app/assets/javascripts/protected_tags/protected_tag_dropdown.js
index 9d045886262d58f2ad7359a27a65effbe0f52338..a0224213aa0b65f63a6c164de4113f927b8f298d 100644
--- a/app/assets/javascripts/protected_tags/protected_tag_dropdown.js
+++ b/app/assets/javascripts/protected_tags/protected_tag_dropdown.js
@@ -1,3 +1,5 @@
+import _ from 'underscore';
+
 export default class ProtectedTagDropdown {
   /**
    * @param {Object} options containing
diff --git a/app/assets/javascripts/right_sidebar.js b/app/assets/javascripts/right_sidebar.js
index d8f1fe10b269484f0fafd40936032062ea744547..fa958d75fa4c9995e14211f42804f482e774ef44 100644
--- a/app/assets/javascripts/right_sidebar.js
+++ b/app/assets/javascripts/right_sidebar.js
@@ -1,5 +1,6 @@
 /* eslint-disable func-names, space-before-function-paren, no-var, prefer-rest-params, wrap-iife, no-unused-vars, consistent-return, one-var, one-var-declaration-per-line, quotes, prefer-template, object-shorthand, comma-dangle, no-else-return, no-param-reassign, max-len */
 
+import _ from 'underscore';
 import Cookies from 'js-cookie';
 import SidebarHeightManager from './sidebar_height_manager';
 
diff --git a/app/assets/javascripts/shortcuts_issuable.js b/app/assets/javascripts/shortcuts_issuable.js
index 51448252c0f4de33050482d6c07d03ea2577aaaa..0be141eb5f9a7b6066ff4e0fd9379b8fbda6923a 100644
--- a/app/assets/javascripts/shortcuts_issuable.js
+++ b/app/assets/javascripts/shortcuts_issuable.js
@@ -3,6 +3,7 @@
 /* global ShortcutsNavigation */
 /* global sidebar */
 
+import _ from 'underscore';
 import 'mousetrap';
 import './shortcuts_navigation';
 
@@ -58,7 +59,7 @@ import './shortcuts_navigation';
       });
       // If replyField already has some content, add a newline before our quote
       separator = replyField.val().trim() !== "" && "\n\n" || '';
-      replyField.val(function(_, current) {
+      replyField.val(function(a, current) {
         return current + separator + quote.join('') + "\n";
       });
 
diff --git a/app/assets/javascripts/sidebar/components/time_tracking/sidebar_time_tracking.js b/app/assets/javascripts/sidebar/components/time_tracking/sidebar_time_tracking.js
index 650e935b1165b3ae0e63bed9a8fc1c7be9770686..2d682215cf80d01ad70a83f3448820c0041f794c 100644
--- a/app/assets/javascripts/sidebar/components/time_tracking/sidebar_time_tracking.js
+++ b/app/assets/javascripts/sidebar/components/time_tracking/sidebar_time_tracking.js
@@ -1,3 +1,5 @@
+import _ from 'underscore';
+
 import '~/smart_interval';
 
 import timeTracker from './time_tracker';
diff --git a/app/assets/javascripts/sidebar_height_manager.js b/app/assets/javascripts/sidebar_height_manager.js
index 022415f22b2cffb08f8707772b230f5180ae5717..df19d7305f822f039eea08839df24cb1c14deb0e 100644
--- a/app/assets/javascripts/sidebar_height_manager.js
+++ b/app/assets/javascripts/sidebar_height_manager.js
@@ -1,3 +1,5 @@
+import _ from 'underscore';
+
 export default {
   init() {
     if (!this.initialized) {
@@ -30,4 +32,3 @@ export default {
     }
   },
 };
-
diff --git a/app/assets/javascripts/todos.js b/app/assets/javascripts/todos.js
index bba8b5abbb46ee32754db8bb7e1af04f6c54118f..a606852c22c27f54f82b5e098858d01af2db207c 100644
--- a/app/assets/javascripts/todos.js
+++ b/app/assets/javascripts/todos.js
@@ -52,6 +52,7 @@ export default class Todos {
   }
 
   updateRowStateClicked(e) {
+    e.stopPropagation();
     e.preventDefault();
 
     const target = e.target;
@@ -92,6 +93,7 @@ export default class Todos {
   }
 
   updateAllStateClicked(e) {
+    e.stopPropagation();
     e.preventDefault();
 
     const target = e.currentTarget;
@@ -142,6 +144,7 @@ export default class Todos {
     if (gl.utils.isMetaClick(e)) {
       const windowTarget = '_blank';
       const selected = e.target;
+      e.stopPropagation();
       e.preventDefault();
 
       if (selected.tagName === 'IMG') {
diff --git a/app/assets/javascripts/u2f/authenticate.js b/app/assets/javascripts/u2f/authenticate.js
index cd5280948fd14a1827262c0d2c747def262b9e38..8821b22477f51a45a855b29115c73c5d9bddf9a0 100644
--- a/app/assets/javascripts/u2f/authenticate.js
+++ b/app/assets/javascripts/u2f/authenticate.js
@@ -3,6 +3,8 @@
 /* global U2FError */
 /* global U2FUtil */
 
+import _ from 'underscore';
+
 // Authenticate U2F (universal 2nd factor) devices for users to authenticate with.
 //
 // State Flow #1: setup -> in_progress -> authenticated -> POST to server
diff --git a/app/assets/javascripts/u2f/register.js b/app/assets/javascripts/u2f/register.js
index 1234d17b8fdfa355a0ff7c5db5a78d9e01a2f051..3a2534d553bec853a2d63f7befec7164ccd22a62 100644
--- a/app/assets/javascripts/u2f/register.js
+++ b/app/assets/javascripts/u2f/register.js
@@ -3,6 +3,8 @@
 /* global U2FError */
 /* global U2FUtil */
 
+import _ from 'underscore';
+
 // Register U2F (universal 2nd factor) devices for users to authenticate with.
 //
 // State Flow #1: setup -> in_progress -> registered -> POST to server
diff --git a/app/assets/javascripts/username_validator.js b/app/assets/javascripts/username_validator.js
index a348d69153cd672404b5f229b780debb9afd4b7c..bb34d5d20086ebd02be94d5af7c2ec7112175390 100644
--- a/app/assets/javascripts/username_validator.js
+++ b/app/assets/javascripts/username_validator.js
@@ -1,5 +1,7 @@
 /* eslint-disable comma-dangle, consistent-return, class-methods-use-this, arrow-parens, no-param-reassign, max-len */
 
+import _ from 'underscore';
+
 const debounceTimeoutDuration = 1000;
 const invalidInputClass = 'gl-field-error-outline';
 const successInputClass = 'gl-field-success-outline';
diff --git a/app/assets/javascripts/users/activity_calendar.js b/app/assets/javascripts/users/activity_calendar.js
index f091e319f44b96cc45b764e4226ffec4ed775d74..3dac31c2121c08c3abc11f9a0494219342f8aad3 100644
--- a/app/assets/javascripts/users/activity_calendar.js
+++ b/app/assets/javascripts/users/activity_calendar.js
@@ -1,3 +1,4 @@
+import _ from 'underscore';
 import d3 from 'd3';
 
 const LOADING_HTML = `
diff --git a/app/assets/javascripts/users_select.js b/app/assets/javascripts/users_select.js
index 5728afb4c5987c27d29dfa6088348a8ae91fd534..16ebf5916dccc579ac449e48ff3684c1a7d89305 100644
--- a/app/assets/javascripts/users_select.js
+++ b/app/assets/javascripts/users_select.js
@@ -1,6 +1,7 @@
 /* eslint-disable func-names, space-before-function-paren, one-var, no-var, prefer-rest-params, wrap-iife, quotes, max-len, one-var-declaration-per-line, vars-on-top, prefer-arrow-callback, consistent-return, comma-dangle, object-shorthand, no-shadow, no-unused-vars, no-else-return, no-self-compare, prefer-template, no-unused-expressions, no-lonely-if, yoda, prefer-spread, no-void, camelcase, no-param-reassign */
 /* global Issuable */
 /* global emitSidebarEvent */
+import _ from 'underscore';
 
 // TODO: remove eventHub hack after code splitting refactor
 window.emitSidebarEvent = window.emitSidebarEvent || $.noop;
diff --git a/app/helpers/defer_script_tag_helper.rb b/app/helpers/defer_script_tag_helper.rb
new file mode 100644
index 0000000000000000000000000000000000000000..e1567556e5ebcd34bc365e926871d0f0ab8c10c8
--- /dev/null
+++ b/app/helpers/defer_script_tag_helper.rb
@@ -0,0 +1,6 @@
+module DeferScriptTagHelper
+  # Override the default ActionView `javascript_include_tag` helper to support page specific deferred loading
+  def javascript_include_tag(*sources)
+    super(*sources, defer: true)
+  end
+end
diff --git a/app/views/layouts/_bootlint.haml b/app/views/layouts/_bootlint.haml
index 69280687a9d87c5c439186c600a6a5b897309081..d603a74c4e468e4046759ab16e030d97d89f30e7 100644
--- a/app/views/layouts/_bootlint.haml
+++ b/app/views/layouts/_bootlint.haml
@@ -1,4 +1,5 @@
+-# haml-lint:disable InlineJavaScript
 :javascript
-  jQuery(document).ready(function() {
-    javascript:(function(){var s=document.createElement("script");s.onload=function(){bootlint.showLintReportForCurrentDocument([], {hasProblems: false, problemFree: false});};s.src="https://maxcdn.bootstrapcdn.com/bootlint/latest/bootlint.min.js";document.body.appendChild(s)})();
-  });
+  window.onload = function() {
+    var s=document.createElement("script");s.onload=function(){bootlint.showLintReportForCurrentDocument([], {hasProblems: false, problemFree: false});};s.src="https://maxcdn.bootstrapcdn.com/bootlint/latest/bootlint.min.js";document.body.appendChild(s);
+  }
diff --git a/app/views/layouts/_init_auto_complete.html.haml b/app/views/layouts/_init_auto_complete.html.haml
index 9704c9ec624c5ceb3cdef40beff322413c8d122b..fe0ec35d0033a9f4824f2643b89800475594cad5 100644
--- a/app/views/layouts/_init_auto_complete.html.haml
+++ b/app/views/layouts/_init_auto_complete.html.haml
@@ -4,6 +4,7 @@
 - if project
   -# haml-lint:disable InlineJavaScript
   :javascript
+    gl = window.gl || {};
     gl.GfmAutoComplete = gl.GfmAutoComplete || {};
     gl.GfmAutoComplete.dataSources = {
       members: "#{members_project_autocomplete_sources_path(project, type: noteable_type, type_id: params[:id])}",
diff --git a/app/views/projects/merge_requests/show.html.haml b/app/views/projects/merge_requests/show.html.haml
index ea6cd16c7ad4c9aae11fb856eeb9b6721ae6fc89..d27e121beb432fda1d546905e888e9e364bc2a6f 100644
--- a/app/views/projects/merge_requests/show.html.haml
+++ b/app/views/projects/merge_requests/show.html.haml
@@ -17,6 +17,7 @@
 
     -# haml-lint:disable InlineJavaScript
     :javascript
+      window.gl = window.gl || {};
       window.gl.mrWidgetData = #{serialize_issuable(@merge_request)}
 
     #js-vue-mr-widget.mr-widget
diff --git a/spec/helpers/defer_script_tag_helper_spec.rb b/spec/helpers/defer_script_tag_helper_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..d10b6f134e4ba7df84773fc49f7baa782cb7b402
--- /dev/null
+++ b/spec/helpers/defer_script_tag_helper_spec.rb
@@ -0,0 +1,13 @@
+# coding: utf-8
+require 'spec_helper'
+
+describe DeferScriptTagHelper do
+  describe 'script tag' do
+    script_url = 'test.js'
+
+    it 'returns an script tag with defer=true' do
+      expect(javascript_include_tag(script_url).to_s)
+        .to eq "<script src=\"/javascripts/#{script_url}\" defer=\"defer\"></script>"
+    end
+  end
+end