Fix eslint prefer-arrow-callback rule

This fixes all disabled lints for the `prefer-arrow-callback` rule:
https://eslint.org/docs/rules/prefer-arrow-callback

app/assets/javascripts/behaviors/preview_markdown.js

-/* eslint-disable func-names, no-var, prefer-arrow-callback */
+/* eslint-disable func-names, no-var */
 
 import $ from 'jquery';
 import axios from '~/lib/utils/axios_utils';
@@ -45,26 +45,22 @@ MarkdownPreview.prototype.showPreview = function($form) {
     this.hideReferencedUsers($form);
   } else {
     preview.addClass('md-preview-loading').text(__('Loading...'));
-    this.fetchMarkdownPreview(
-      mdText,
-      url,
-      function(response) {
-        var body;
-        if (response.body.length > 0) {
-          ({ body } = response);
-        } else {
-          body = this.emptyMessage;
-        }
-
-        preview.removeClass('md-preview-loading').html(body);
-        preview.renderGFM();
-        this.renderReferencedUsers(response.references.users, $form);
-
-        if (response.references.commands) {
-          this.renderReferencedCommands(response.references.commands, $form);
-        }
-      }.bind(this),
-    );
+    this.fetchMarkdownPreview(mdText, url, response => {
+      var body;
+      if (response.body.length > 0) {
+        ({ body } = response);
+      } else {
+        body = this.emptyMessage;
+      }
+
+      preview.removeClass('md-preview-loading').html(body);
+      preview.renderGFM();
+      this.renderReferencedUsers(response.references.users, $form);
+
+      if (response.references.commands) {
+        this.renderReferencedCommands(response.references.commands, $form);
+      }
+    });
   }
 };
 
@@ -132,12 +128,12 @@ const markdownToolbar = $('.md-header-toolbar');
 
 $.fn.setupMarkdownPreview = function() {
   var $form = $(this);
-  $form.find('textarea.markdown-area').on('input', function() {
+  $form.find('textarea.markdown-area').on('input', () => {
     markdownPreview.hideReferencedUsers($form);
   });
 };
 
-$(document).on('markdown-preview:show', function(e, $form) {
+$(document).on('markdown-preview:show', (e, $form) => {
   if (!$form) {
     return;
   }
@@ -162,7 +158,7 @@ $(document).on('markdown-preview:show', function(e, $form) {
   markdownPreview.showPreview($form);
 });
 
-$(document).on('markdown-preview:hide', function(e, $form) {
+$(document).on('markdown-preview:hide', (e, $form) => {
   if (!$form) {
     return;
   }
@@ -191,7 +187,7 @@ $(document).on('markdown-preview:hide', function(e, $form) {
   markdownPreview.hideReferencedCommands($form);
 });
 
-$(document).on('markdown-preview:toggle', function(e, keyboardEvent) {
+$(document).on('markdown-preview:toggle', (e, keyboardEvent) => {
   var $target;
   $target = $(keyboardEvent.target);
   if ($target.is('textarea.markdown-area')) {

app/assets/javascripts/blob/blob_file_dropzone.js

-/* eslint-disable func-names, prefer-arrow-callback */
+/* eslint-disable func-names */
 
 import $ from 'jquery';
 import Dropzone from 'dropzone';
@@ -43,18 +43,18 @@ export default class BlobFileDropzone {
       previewsContainer: '.dropzone-previews',
       headers: csrf.headers,
       init() {
-        this.on('addedfile', function() {
+        this.on('addedfile', () => {
           toggleLoading(submitButton, submitButtonLoadingIcon, false);
           dropzoneMessage.addClass(HIDDEN_CLASS);
           $('.dropzone-alerts')
             .html('')
             .hide();
         });
-        this.on('removedfile', function() {
+        this.on('removedfile', () => {
           toggleLoading(submitButton, submitButtonLoadingIcon, false);
           dropzoneMessage.removeClass(HIDDEN_CLASS);
         });
-        this.on('success', function(header, response) {
+        this.on('success', (header, response) => {
           $('#modal-upload-blob').modal('hide');
           visitUrl(response.filePath);
         });
@@ -62,7 +62,7 @@ export default class BlobFileDropzone {
           dropzoneMessage.addClass(HIDDEN_CLASS);
           this.removeFile(file);
         });
-        this.on('sending', function(file, xhr, formData) {
+        this.on('sending', (file, xhr, formData) => {
           formData.append('branch_name', form.find('.js-branch-name').val());
           formData.append('create_merge_request', form.find('.js-create-merge-request').val());
           formData.append('commit_message', form.find('.js-commit-message').val());

app/assets/javascripts/build_artifacts.js

-/* eslint-disable func-names, prefer-arrow-callback */
+/* eslint-disable func-names */
 
 import $ from 'jquery';
 import { visitUrl } from './lib/utils/url_utility';
@@ -12,11 +12,11 @@ export default class BuildArtifacts {
   }
   // eslint-disable-next-line class-methods-use-this
   disablePropagation() {
-    $('.top-block').on('click', '.download', function(e) {
-      return e.stopPropagation();
+    $('.top-block').on('click', '.download', e => {
+      e.stopPropagation();
     });
-    return $('.tree-holder').on('click', 'tr[data-link] a', function(e) {
-      return e.stopImmediatePropagation();
+    return $('.tree-holder').on('click', 'tr[data-link] a', e => {
+      e.stopImmediatePropagation();
     });
   }
   // eslint-disable-next-line class-methods-use-this

app/assets/javascripts/commit/image_file.js

-/* eslint-disable func-names, no-var, prefer-arrow-callback, no-else-return, consistent-return, prefer-template, one-var, no-return-assign, no-unused-expressions, no-sequences */
+/* eslint-disable func-names, no-var, no-else-return, consistent-return, prefer-template, one-var, no-return-assign, no-unused-expressions, no-sequences */
 
 import $ from 'jquery';
 
@@ -13,14 +13,14 @@ export default class ImageFile {
       $('.two-up.view .frame.deleted img', this.file),
       (function(_this) {
         return function() {
-          return _this.requestImageInfo($('.two-up.view .frame.added img', _this.file), function() {
+          return _this.requestImageInfo($('.two-up.view .frame.added img', _this.file), () => {
             _this.initViewModes();
 
             // Load two-up view after images are loaded
             // so that we can display the correct width and height information
             const $images = $('.two-up.view img', _this.file);
 
-            $images.waitForImages(function() {
+            $images.waitForImages(() => {
               _this.initView('two-up');
             });
           });
@@ -138,7 +138,7 @@ export default class ImageFile {
                 return $(this).width(availWidth / 2);
               }
             });
-            return _this.requestImageInfo($('img', wrap), function(width, height) {
+            return _this.requestImageInfo($('img', wrap), (width, height) => {
               $('.image-info .meta-width', wrap).text(width + 'px');
               $('.image-info .meta-height', wrap).text(height + 'px');
               return $('.image-info', wrap).removeClass('hide');
@@ -175,7 +175,7 @@ export default class ImageFile {
 
             wrapPadding = parseInt($swipeWrap.css('right').replace('px', ''), 10);
 
-            _this.initDraggable($swipeBar, wrapPadding, function(e, left) {
+            _this.initDraggable($swipeBar, wrapPadding, (e, left) => {
               if (left > 0 && left < $swipeFrame.width() - wrapPadding * 2) {
                 $swipeWrap.width(maxWidth + 1 - left);
                 $swipeBar.css('left', left);
@@ -215,7 +215,7 @@ export default class ImageFile {
             $frameAdded.css('opacity', 1);
             framePadding = parseInt($frameAdded.css('right').replace('px', ''), 10);
 
-            _this.initDraggable($dragger, framePadding, function(e, left) {
+            _this.initDraggable($dragger, framePadding, (e, left) => {
               var opacity = left / dragTrackWidth;
 
               if (opacity >= 0 && opacity <= 1) {

app/assets/javascripts/create_label.js

-/* eslint-disable func-names, prefer-arrow-callback */
+/* eslint-disable func-names */
 
 import $ from 'jquery';
 import Api from './api';
@@ -50,7 +50,7 @@ export default class CreateLabelDropdown {
 
     this.$dropdownBack.on('click', this.resetForm.bind(this));
 
-    this.$cancelButton.on('click', function(e) {
+    this.$cancelButton.on('click', e => {
       e.preventDefault();
       e.stopPropagation();
 

app/assets/javascripts/gl_dropdown.js

-/* eslint-disable func-names, no-underscore-dangle, no-var, one-var, vars-on-top, no-shadow, no-cond-assign, prefer-arrow-callback, no-return-assign, no-else-return, camelcase, no-lonely-if, guard-for-in, no-restricted-syntax, consistent-return, prefer-template, no-param-reassign, no-loop-func */
+/* eslint-disable func-names, no-underscore-dangle, no-var, one-var, vars-on-top, no-shadow, no-cond-assign, no-return-assign, no-else-return, camelcase, no-lonely-if, guard-for-in, no-restricted-syntax, consistent-return, prefer-template, no-param-reassign, no-loop-func */
 
 import $ from 'jquery';
 import _ from 'underscore';
@@ -35,13 +35,13 @@ GitLabDropdownInput = (function() {
     );
 
     this.input
-      .on('keydown', function(e) {
+      .on('keydown', e => {
         var keyCode = e.which;
         if (keyCode === 13 && !options.elIsInput) {
           e.preventDefault();
         }
       })
-      .on('input', function(e) {
+      .on('input', e => {
         var val = e.currentTarget.value || _this.options.inputFieldName;
         val = val
           .split(' ')
@@ -95,42 +95,33 @@ GitLabDropdownFilter = (function() {
     // Key events
     timeout = '';
     this.input
-      .on('keydown', function(e) {
+      .on('keydown', e => {
         var keyCode = e.which;
         if (keyCode === 13 && !options.elIsInput) {
           e.preventDefault();
         }
       })
-      .on(
-        'input',
-        function() {
-          if (this.input.val() !== '' && !$inputContainer.hasClass(HAS_VALUE_CLASS)) {
-            $inputContainer.addClass(HAS_VALUE_CLASS);
-          } else if (this.input.val() === '' && $inputContainer.hasClass(HAS_VALUE_CLASS)) {
-            $inputContainer.removeClass(HAS_VALUE_CLASS);
-          }
-          // Only filter asynchronously only if option remote is set
-          if (this.options.remote) {
-            clearTimeout(timeout);
-            return (timeout = setTimeout(
-              function() {
-                $inputContainer.parent().addClass('is-loading');
-
-                return this.options.query(
-                  this.input.val(),
-                  function(data) {
-                    $inputContainer.parent().removeClass('is-loading');
-                    return this.options.callback(data);
-                  }.bind(this),
-                );
-              }.bind(this),
-              250,
-            ));
-          } else {
-            return this.filter(this.input.val());
-          }
-        }.bind(this),
-      );
+      .on('input', () => {
+        if (this.input.val() !== '' && !$inputContainer.hasClass(HAS_VALUE_CLASS)) {
+          $inputContainer.addClass(HAS_VALUE_CLASS);
+        } else if (this.input.val() === '' && $inputContainer.hasClass(HAS_VALUE_CLASS)) {
+          $inputContainer.removeClass(HAS_VALUE_CLASS);
+        }
+        // Only filter asynchronously only if option remote is set
+        if (this.options.remote) {
+          clearTimeout(timeout);
+          return (timeout = setTimeout(() => {
+            $inputContainer.parent().addClass('is-loading');
+
+            return this.options.query(this.input.val(), data => {
+              $inputContainer.parent().removeClass('is-loading');
+              return this.options.callback(data);
+            });
+          }, 250));
+        } else {
+          return this.filter(this.input.val());
+        }
+      });
   }
 
   GitLabDropdownFilter.prototype.shouldBlur = function(keyCode) {
@@ -175,9 +166,7 @@ GitLabDropdownFilter = (function() {
                 key: this.options.keys,
               });
               if (tmp.length) {
-                results[key] = tmp.map(function(item) {
-                  return item;
-                });
+                results[key] = tmp.map(item => item);
               }
             }
           }
@@ -453,32 +442,28 @@ GitLabDropdown = (function() {
       if (this.dropdown.find('.dropdown-toggle-page').length) {
         selector = '.dropdown-page-one .dropdown-content a';
       }
-      this.dropdown.on(
-        'click',
-        selector,
-        function(e) {
-          var $el, selected, selectedObj, isMarking;
-          $el = $(e.currentTarget);
-          selected = self.rowClicked($el);
-          selectedObj = selected ? selected[0] : null;
-          isMarking = selected ? selected[1] : null;
-          if (this.options.clicked) {
-            this.options.clicked.call(this, {
-              selectedObj,
-              $el,
-              e,
-              isMarking,
-            });
-          }
+      this.dropdown.on('click', selector, e => {
+        var $el, selected, selectedObj, isMarking;
+        $el = $(e.currentTarget);
+        selected = self.rowClicked($el);
+        selectedObj = selected ? selected[0] : null;
+        isMarking = selected ? selected[1] : null;
+        if (this.options.clicked) {
+          this.options.clicked.call(this, {
+            selectedObj,
+            $el,
+            e,
+            isMarking,
+          });
+        }
 
-          // Update label right after all modifications in dropdown has been done
-          if (this.options.toggleLabel) {
-            this.updateLabel(selectedObj, $el, this);
-          }
+        // Update label right after all modifications in dropdown has been done
+        if (this.options.toggleLabel) {
+          this.updateLabel(selectedObj, $el, this);
+        }
 
-          $el.trigger('blur');
-        }.bind(this),
-      );
+        $el.trigger('blur');
+      });
     }
   }
 
@@ -525,9 +510,7 @@ GitLabDropdown = (function() {
               name,
             ),
           );
-          this.renderData(groupData, name).map(function(item) {
-            return html.push(item);
-          });
+          this.renderData(groupData, name).map(item => html.push(item));
         }
       } else {
         // Render each row
@@ -708,7 +691,7 @@ GitLabDropdown = (function() {
 
     return text
       .split('')
-      .map(function(character, i) {
+      .map((character, i) => {
         if (indexOf.call(occurrences, i) !== -1) {
           return '<b>' + character + '</b>';
         } else {

app/assets/javascripts/issuable_bulk_update_actions.js

-/* eslint-disable consistent-return, func-names, array-callback-return, prefer-arrow-callback */
+/* eslint-disable consistent-return, func-names, array-callback-return */
 
 import $ from 'jquery';
 import _ from 'underscore';
@@ -45,7 +45,7 @@ export default {
     this.getSelectedIssues().map(function() {
       const labelsData = $(this).data('labels');
       if (labelsData) {
-        return labelsData.map(function(labelId) {
+        return labelsData.map(labelId => {
           if (labels.indexOf(labelId) === -1) {
             return labels.push(labelId);
           }

app/assets/javascripts/labels_select.js

-/* eslint-disable no-useless-return, func-names, no-var, no-underscore-dangle, prefer-arrow-callback, one-var, prefer-template, no-new, consistent-return, no-shadow, no-param-reassign, vars-on-top, no-lonely-if, no-else-return, dot-notation, no-empty */
+/* eslint-disable no-useless-return, func-names, no-var, no-underscore-dangle, one-var, prefer-template, no-new, consistent-return, no-shadow, no-param-reassign, vars-on-top, no-lonely-if, no-else-return, dot-notation, no-empty */
 /* global Issuable */
 /* global ListLabel */
 
@@ -24,7 +24,7 @@ export default class LabelsSelect {
       $els = $('.js-label-select');
     }
 
-    $els.each(function(i, dropdown) {
+    $els.each((i, dropdown) => {
       var $block,
         $dropdown,
         $form,
@@ -172,9 +172,7 @@ export default class LabelsSelect {
             $sidebarCollapsedValue.text(labelCount);
 
             if (data.labels.length) {
-              labelTitles = data.labels.map(function(label) {
-                return label.title;
-              });
+              labelTitles = data.labels.map(label => label.title);
 
               if (labelTitles.length > 5) {
                 labelTitles = labelTitles.slice(0, 5);
@@ -456,9 +454,7 @@ export default class LabelsSelect {
               );
             } else {
               var { labels } = boardsStore.detail.issue;
-              labels = labels.filter(function(selectedLabel) {
-                return selectedLabel.id !== label.id;
-              });
+              labels = labels.filter(selectedLabel => selectedLabel.id !== label.id);
               boardsStore.detail.issue.labels = labels;
             }
 

app/assets/javascripts/lib/utils/notify.js

-/* eslint-disable func-names, no-var, consistent-return, prefer-arrow-callback, no-return-assign */
+/* eslint-disable no-var, consistent-return, no-return-assign */
 
 function notificationGranted(message, opts, onclick) {
   var notification;
   notification = new Notification(message, opts);
-  setTimeout(function() {
-    // Hide the notification after X amount of seconds
-    return notification.close();
-  }, 8000);
+  setTimeout(
+    () =>
+      // Hide the notification after X amount of seconds
+      notification.close(),
+    8000,
+  );
 
   return (notification.onclick = onclick || notification.close);
 }
@@ -32,7 +34,7 @@ function notifyMe(message, body, icon, onclick) {
     // If it's okay let's create a notification
     return notificationGranted(message, opts, onclick);
   } else if (Notification.permission !== 'denied') {
-    return Notification.requestPermission(function(permission) {
+    return Notification.requestPermission(permission => {
       // If the user accepts, let's create a notification
       if (permission === 'granted') {
         return notificationGranted(message, opts, onclick);

app/assets/javascripts/lib/utils/text_markdown.js

-/* eslint-disable func-names, no-var, no-param-reassign, one-var, operator-assignment, no-else-return, prefer-template, prefer-arrow-callback, consistent-return */
+/* eslint-disable func-names, no-var, no-param-reassign, one-var, operator-assignment, no-else-return, prefer-template, consistent-return */
 import $ from 'jquery';
 import { insertText } from '~/lib/utils/common_utils';
 
@@ -218,7 +218,7 @@ export function insertMarkdownText({
         : blockTagText(text, textArea, blockTag, selected);
     } else {
       textToInsert = selectedSplit
-        .map(function(val) {
+        .map(val => {
           if (tag.indexOf(textPlaceholder) > -1) {
             return tag.replace(textPlaceholder, val);
           }
@@ -301,7 +301,7 @@ export function addMarkdownListeners(form) {
 export function addEditorMarkdownListeners(editor) {
   $('.js-md')
     .off('click')
-    .on('click', function(e) {
+    .on('click', e => {
       const { mdTag, mdBlock, mdPrepend, mdSelect } = $(e.currentTarget).data();
 
       insertMarkdownText({

app/assets/javascripts/merge_request.js

-/* eslint-disable func-names, no-var, no-underscore-dangle, one-var, consistent-return, prefer-arrow-callback */
+/* eslint-disable func-names, no-var, no-underscore-dangle, one-var, consistent-return */
 
 import $ from 'jquery';
 import { __ } from '~/locale';
@@ -105,7 +105,7 @@ MergeRequest.prototype.submitNoteForm = function(form, $button) {
 };
 
 MergeRequest.prototype.initCommitMessageListeners = function() {
-  $(document).on('click', 'a.js-with-description-link', function(e) {
+  $(document).on('click', 'a.js-with-description-link', e => {
     var textarea = $('textarea.js-commit-message');
     e.preventDefault();
 
@@ -114,7 +114,7 @@ MergeRequest.prototype.initCommitMessageListeners = function() {
     $('.js-without-description-hint').show();
   });
 
-  $(document).on('click', 'a.js-without-description-link', function(e) {
+  $(document).on('click', 'a.js-without-description-link', e => {
     var textarea = $('textarea.js-commit-message');
     e.preventDefault();
 

app/assets/javascripts/namespace_select.js

-/* eslint-disable func-names, no-else-return, prefer-template, prefer-arrow-callback */
+/* eslint-disable no-else-return, prefer-template */
 
 import $ from 'jquery';
 import Api from './api';
@@ -27,7 +27,7 @@ export default class NamespaceSelect {
         }
       },
       data(term, dataCallback) {
-        return Api.namespaces(term, function(namespaces) {
+        return Api.namespaces(term, namespaces => {
           if (isFilter) {
             const anyNamespace = {
               text: __('Any namespace'),

app/assets/javascripts/network/branch_graph.js

-/* eslint-disable func-names, no-var, one-var, no-loop-func, consistent-return, prefer-template, prefer-arrow-callback, camelcase */
+/* eslint-disable func-names, no-var, one-var, no-loop-func, consistent-return, prefer-template, camelcase */
 
 import $ from 'jquery';
 import { __ } from '../locale';
@@ -259,9 +259,7 @@ export default (function() {
         opacity: 0,
         cursor: 'pointer',
       })
-      .click(function() {
-        return window.open(options.commit_url.replace('%s', commit.id), '_blank');
-      })
+      .click(() => window.open(options.commit_url.replace('%s', commit.id), '_blank'))
       .hover(
         function() {
           this.tooltip = r.commitTooltip(x + 5, y, commit);

app/assets/javascripts/new_branch_form.js

-/* eslint-disable func-names, no-var, one-var, consistent-return, no-return-assign, prefer-arrow-callback, prefer-template, no-shadow, no-else-return, @gitlab/i18n/no-non-i18n-strings */
+/* eslint-disable func-names, no-var, one-var, consistent-return, no-return-assign, prefer-template, no-shadow, no-else-return, @gitlab/i18n/no-non-i18n-strings */
 
 import $ from 'jquery';
 import RefSelectDropdown from './ref_select_dropdown';
@@ -63,7 +63,7 @@ export default class NewBranchForm {
     };
     formatter = function(values, restriction) {
       var formatted;
-      formatted = values.map(function(value) {
+      formatted = values.map(value => {
         switch (false) {
           case !/\s/.test(value):
             return 'spaces';

app/assets/javascripts/notes.js

 /* eslint-disable no-restricted-properties, func-names, no-var, camelcase,
 no-unused-expressions, one-var, default-case,
 prefer-template, consistent-return, no-alert, no-return-assign,
-no-param-reassign, prefer-arrow-callback, no-else-return, vars-on-top,
+no-param-reassign, no-else-return, vars-on-top,
 no-shadow, no-useless-escape, class-methods-use-this */
 
 /* global ResolveService */
@@ -1370,7 +1370,7 @@ export default class Notes {
       .find('li.system-note')
       .has('ul');
 
-    $.each(systemNotes, function(index, systemNote) {
+    $.each(systemNotes, (index, systemNote) => {
       const $systemNote = $(systemNote);
       const headerMessage = $systemNote
         .find('.note-text')

app/assets/javascripts/pages/projects/graphs/show/stat_graph_contributors_graph.js

-/* eslint-disable func-names, no-restricted-syntax, no-use-before-define, no-param-reassign, new-cap, no-underscore-dangle, no-return-assign, prefer-arrow-callback, prefer-template, no-else-return, no-shadow */
+/* eslint-disable func-names, no-restricted-syntax, no-use-before-define, no-param-reassign, new-cap, no-underscore-dangle, no-return-assign, prefer-template, no-else-return, no-shadow */
 
 import $ from 'jquery';
 import _ from 'underscore';
@@ -69,24 +69,18 @@ export const ContributorsGraph = (function() {
   ContributorsGraph.set_y_domain = function(data) {
     return (ContributorsGraph.prototype.y_domain = [
       0,
-      d3.max(data, function(d) {
-        return (d.commits = d.commits || d.additions || d.deletions);
-      }),
+      d3.max(data, d => (d.commits = d.commits || d.additions || d.deletions)),
     ]);
   };
 
   ContributorsGraph.init_x_domain = function(data) {
-    return (ContributorsGraph.prototype.x_domain = d3.extent(data, function(d) {
-      return d.date;
-    }));
+    return (ContributorsGraph.prototype.x_domain = d3.extent(data, d => d.date));
   };
 
   ContributorsGraph.init_y_domain = function(data) {
     return (ContributorsGraph.prototype.y_domain = [
       0,
-      d3.max(data, function(d) {
-        return (d.commits = d.commits || d.additions || d.deletions);
-      }),
+      d3.max(data, d => (d.commits = d.commits || d.additions || d.deletions)),
     ]);
   };
 
@@ -180,9 +174,7 @@ export const ContributorsMasterGraph = (function(superClass) {
 
   ContributorsMasterGraph.prototype.parse_dates = function(data) {
     const parseDate = d3.timeParse('%Y-%m-%d');
-    return data.forEach(function(d) {
-      return (d.date = parseDate(d.date));
-    });
+    return data.forEach(d => (d.date = parseDate(d.date)));
   };
 
   ContributorsMasterGraph.prototype.create_scale = function() {
@@ -216,11 +208,9 @@ export const ContributorsMasterGraph = (function(superClass) {
   ContributorsMasterGraph.prototype.create_area = function(x, y) {
     return (this.area = d3
       .area()
-      .x(function(d) {
-        return x(d.date);
-      })
+      .x(d => x(d.date))
       .y0(this.height)
-      .y1(function(d) {
+      .y1(d => {
         d.commits = d.commits || d.additions || d.deletions;
         return y(d.commits);
       }));
@@ -330,7 +320,7 @@ export const ContributorsAuthorGraph = (function(superClass) {
   ContributorsAuthorGraph.prototype.create_area = function(x, y) {
     return (this.area = d3
       .area()
-      .x(function(d) {
+      .x(d => {
         const parseDate = d3.timeParse('%Y-%m-%d');
         return x(parseDate(d));
       })

app/assets/javascripts/pages/projects/graphs/show/stat_graph_contributors_util.js

-/* eslint-disable func-names, no-var, one-var, camelcase, no-param-reassign, no-return-assign, prefer-arrow-callback, consistent-return, no-cond-assign, no-else-return */
+/* eslint-disable func-names, no-var, one-var, camelcase, no-param-reassign, no-return-assign, consistent-return, no-cond-assign, no-else-return */
 import _ from 'underscore';
 
 export default {
@@ -76,16 +76,12 @@ export default {
     var log, total_data;
     log = parsed_log.total;
     total_data = this.pick_field(log, field);
-    return _.sortBy(total_data, function(d) {
-      return d.date;
-    });
+    return _.sortBy(total_data, d => d.date);
   },
   pick_field(log, field) {
     var total_data;
     total_data = [];
-    _.each(log, function(d) {
-      return total_data.push(_.pick(d, [field, 'date']));
-    });
+    _.each(log, d => total_data.push(_.pick(d, [field, 'date'])));
     return total_data;
   },
   get_author_data(parsed_log, field, date_range) {
@@ -107,9 +103,7 @@ export default {
         };
       })(this),
     );
-    return _.sortBy(author_data, function(d) {
-      return d[field];
-    }).reverse();
+    return _.sortBy(author_data, d => d[field]).reverse();
   },
   parse_log_entry(log_entry, field, date_range) {
     var parsed_entry;

app/assets/javascripts/single_file_diff.js

-/* eslint-disable func-names, prefer-arrow-callback, consistent-return, */
+/* eslint-disable consistent-return */
 
 import $ from 'jquery';
 import { __ } from './locale';
@@ -40,12 +40,9 @@ export default class SingleFileDiff {
       this.$toggleIcon.addClass('fa-caret-down');
     }
 
-    $('.js-file-title, .click-to-expand', this.file).on(
-      'click',
-      function(e) {
-        this.toggleDiff($(e.target));
-      }.bind(this),
-    );
+    $('.js-file-title, .click-to-expand', this.file).on('click', e => {
+      this.toggleDiff($(e.target));
+    });
   }
 
   toggleDiff($target, cb) {

app/assets/javascripts/tree.js

-/* eslint-disable func-names, consistent-return, no-var, one-var, no-else-return, prefer-arrow-callback, class-methods-use-this */
+/* eslint-disable func-names, consistent-return, no-var, one-var, no-else-return, class-methods-use-this */
 
 import $ from 'jquery';
 import { visitUrl } from './lib/utils/url_utility';
@@ -29,7 +29,7 @@ export default class TreeView {
     var li, liSelected;
     li = $('tr.tree-item');
     liSelected = null;
-    return $('body').keydown(function(e) {
+    return $('body').keydown(e => {
       var next, path;
       if ($('input:focus').length > 0 && (e.which === 38 || e.which === 40)) {
         return false;

app/assets/javascripts/users_select.js

-/* eslint-disable func-names, one-var, no-var, prefer-rest-params, vars-on-top, prefer-arrow-callback, consistent-return, no-shadow, no-else-return, no-self-compare, prefer-template, no-unused-expressions, yoda, prefer-spread, camelcase, no-param-reassign */
+/* eslint-disable func-names, one-var, no-var, prefer-rest-params, vars-on-top, consistent-return, no-shadow, no-else-return, no-self-compare, prefer-template, no-unused-expressions, yoda, prefer-spread, camelcase, no-param-reassign */
 /* global Issuable */
 /* global emitSidebarEvent */
 
@@ -250,16 +250,12 @@ function UsersSelect(currentUser, els, options = {}) {
         return $dropdown.glDropdown({
           showMenuAbove,
           data(term, callback) {
-            return _this.users(
-              term,
-              options,
-              function(users) {
-                // GitLabDropdownFilter returns this.instance
-                // GitLabDropdownRemote returns this.options.instance
-                const glDropdown = this.instance || this.options.instance;
-                glDropdown.options.processData(term, users, callback);
-              }.bind(this),
-            );
+            return _this.users(term, options, users => {
+              // GitLabDropdownFilter returns this.instance
+              // GitLabDropdownRemote returns this.options.instance
+              const glDropdown = this.instance || this.options.instance;
+              glDropdown.options.processData(term, users, callback);
+            });
           },
           processData(term, data, callback) {
             let users = data;
@@ -606,7 +602,7 @@ function UsersSelect(currentUser, els, options = {}) {
               multiple: $(select).hasClass('multiselect'),
               minimumInputLength: 0,
               query(query) {
-                return _this.users(query.term, options, function(users) {
+                return _this.users(query.term, options, users => {
                   var anyUser, data, emailUser, index, len, name, nullUser, obj, ref;
                   data = {
                     results: users,

app/assets/javascripts/zen_mode.js

-/* eslint-disable func-names, prefer-arrow-callback, consistent-return, camelcase, class-methods-use-this */
+/* eslint-disable func-names, consistent-return, camelcase, class-methods-use-this */
 
 // Zen Mode (full screen) textarea
 //
@@ -39,11 +39,11 @@ export default class ZenMode {
   constructor() {
     this.active_backdrop = null;
     this.active_textarea = null;
-    $(document).on('click', '.js-zen-enter', function(e) {
+    $(document).on('click', '.js-zen-enter', e => {
       e.preventDefault();
       return $(e.currentTarget).trigger('zen_mode:enter');
     });
-    $(document).on('click', '.js-zen-leave', function(e) {
+    $(document).on('click', '.js-zen-leave', e => {
       e.preventDefault();
       return $(e.currentTarget).trigger('zen_mode:leave');
     });
@@ -67,7 +67,7 @@ export default class ZenMode {
         };
       })(this),
     );
-    $(document).on('keydown', function(e) {
+    $(document).on('keydown', e => {
       // Esc
       if (e.keyCode === 27) {
         e.preventDefault();

ee/app/assets/javascripts/ldap_groups_select.js

-/* eslint-disable prefer-arrow-callback, no-var, one-var, consistent-return, func-names */
+/* eslint-disable no-var, one-var, consistent-return, func-names */
 
 import $ from 'jquery';
 import Api from 'ee/api';
@@ -14,8 +14,8 @@ export default function initLDAPGroupsSelect() {
   };
   import(/* webpackChunkName: 'select2' */ 'select2/select2')
     .then(() => {
-      $('.ajax-ldap-groups-select').each(function(i, select) {
-        return $(select).select2({
+      $('.ajax-ldap-groups-select').each((i, select) => {
+        $(select).select2({
           id(group) {
             return group.cn;
           },
@@ -24,7 +24,7 @@ export default function initLDAPGroupsSelect() {
           query(query) {
             var provider;
             provider = $('#ldap_group_link_provider').val();
-            return Api.ldapGroups(query.term, provider, function(groups) {
+            return Api.ldapGroups(query.term, provider, groups => {
               var data;
               data = {
                 results: groups,
@@ -52,7 +52,7 @@ export default function initLDAPGroupsSelect() {
     })
     .catch(() => {});
 
-  return $('#ldap_group_link_provider').on('change', function() {
-    return $('.ajax-ldap-groups-select').select2('data', null);
+  $('#ldap_group_link_provider').on('change', () => {
+    $('.ajax-ldap-groups-select').select2('data', null);
   });
 }

ee/app/assets/javascripts/pages/admin/emails/show/admin_email_select.js

-/* eslint-disable no-var, func-names, one-var, prefer-arrow-callback, prefer-template, no-else-return */
+/* eslint-disable no-var, func-names, one-var, prefer-template, no-else-return */
 
 import $ from 'jquery';
 import Api from '~/api';
@@ -20,7 +20,7 @@ function AdminEmailSelect() {
                   order_by: 'id',
                   membership: false,
                 });
-                return Promise.all([projectsFetch, groupsFetch]).then(function([projects, groups]) {
+                return Promise.all([projectsFetch, groupsFetch]).then(([projects, groups]) => {
                   var all, data;
                   all = {
                     id: 'all',

ee/app/assets/javascripts/weight_select.js

-/* eslint-disable prefer-arrow-callback, one-var, no-var, no-shadow, no-else-return, func-names */
+/* eslint-disable one-var, no-var, no-shadow, no-else-return */
 
 import $ from 'jquery';
 import '~/gl_dropdown';
@@ -6,7 +6,7 @@ import '~/gl_dropdown';
 function WeightSelect(els, options = {}) {
   const $els = $(els || '.js-weight-select');
 
-  $els.each(function(i, dropdown) {
+  $els.each((i, dropdown) => {
     var $block, $dropdown, $selectbox, $value;
     $dropdown = $(dropdown);
     $selectbox = $dropdown.closest('.selectbox');