Stop using `_.isUndefined`

spec/bookmarks.js

@@ -161,7 +161,7 @@
                 'name':  'The Lounge',
                 'nick': ' Othello'
             });
-            expect(_.isUndefined(_converse.chatboxviews.get(jid))).toBeTruthy();
+            expect(_converse.chatboxviews.get(jid) === undefined).toBeTruthy();
 
             jid = 'theplay@conference.shakespeare.lit';
             _converse.bookmarks.create({
@@ -170,7 +170,7 @@
                 'name':  'The Play',
                 'nick': ' Othello'
             });
-            expect(_.isUndefined(_converse.chatboxviews.get(jid))).toBeFalsy();
+            expect(_converse.chatboxviews.get(jid) === undefined).toBeFalsy();
 
             // Check that we don't auto-join if muc_respect_autojoin is false
             _converse.muc_respect_autojoin = false;
@@ -181,7 +181,7 @@
                 'name':  'Balcony',
                 'nick': ' Othello'
             });
-            expect(_.isUndefined(_converse.chatboxviews.get(jid))).toBe(true);
+            expect(_converse.chatboxviews.get(jid) === undefined).toBe(true);
             done();
         }));
 

spec/roomslist.js

@@ -19,7 +19,7 @@
             expect(_.includes(list.classList, 'hidden')).toBeTruthy();
 
             await test_utils.openChatRoom(_converse, 'room', 'conference.shakespeare.lit', 'JC');
-            expect(_.isUndefined(_converse.rooms_list_view)).toBeFalsy();
+            expect(_converse.rooms_list_view === undefined).toBeFalsy();
 
             const lview = _converse.rooms_list_view
             await u.waitUntil(() => lview.el.querySelectorAll(".open-room").length);
@@ -288,7 +288,7 @@
 
             test_utils.openControlBox();
             const room_jid = 'kitchen@conference.shakespeare.lit';
-            await u.waitUntil(() => !_.isUndefined(_converse.rooms_list_view), 500);
+            await u.waitUntil(() => _converse.rooms_list_view !== undefined, 500);
             await test_utils.openAndEnterChatRoom(_converse, 'kitchen@conference.shakespeare.lit', 'romeo');
             const view = _converse.chatboxviews.get(room_jid);
             view.model.set({'minimized': true});

src/converse-bookmark-views.js

@@ -129,7 +129,7 @@ converse.plugins.add('converse-bookmark-views', {
             setBookmarkState () {
                 /* Set whether the groupchat is bookmarked or not.
                  */
-                if (!_.isUndefined(_converse.bookmarks)) {
+                if (_converse.bookmarks !== undefined) {
                     const models = _converse.bookmarks.where({'jid': this.model.get('jid')});
                     if (!models.length) {
                         this.model.save('bookmarked', false);
@@ -278,7 +278,7 @@ converse.plugins.add('converse-bookmark-views', {
 
             insertIntoControlBox () {
                 const controlboxview = _converse.chatboxviews.get('controlbox');
-                if (!_.isUndefined(controlboxview) && !u.rootContains(_converse.root, this.el)) {
+                if (controlboxview !== undefined && !u.rootContains(_converse.root, this.el)) {
                     const el = controlboxview.el.querySelector('.bookmarks-list');
                     if (!_.isNull(el)) {
                         el.parentNode.replaceChild(this.el, el);

src/converse-chatview.js

@@ -251,13 +251,13 @@ converse.plugins.add('converse-chatview', {
                     '_converse': _converse,
                     'allow_contact_removal': _converse.allow_contact_removal,
                     'display_name': this.model.getDisplayName(),
-                    'is_roster_contact': !_.isUndefined(this.model.contact),
+                    'is_roster_contact': this.model.contact !== undefined,
                     'utils': u
                 }));
             },
 
             registerContactEventHandlers () {
-                if (!_.isUndefined(this.model.contact)) {
+                if (this.model.contact !== undefined) {
                     this.model.contact.on('change', this.render, this);
                     this.model.contact.vcard.on('change', this.render, this);
                     this.model.contact.on('destroy', () => {
@@ -447,7 +447,7 @@ converse.plugins.add('converse-chatview', {
 
             showUserDetailsModal (ev) {
                 ev.preventDefault();
-                if (_.isUndefined(this.user_details_modal)) {
+                if (this.user_details_modal === undefined) {
                     this.user_details_modal = new _converse.UserDetailsModal({model: this.model});
                 }
                 this.user_details_modal.show(ev);
@@ -518,7 +518,7 @@ converse.plugins.add('converse-chatview', {
                 this.heading.render();
                 this.heading.chatview = this;
 
-                if (!_.isUndefined(this.model.contact)) {
+                if (this.model.contact !== undefined) {
                     this.model.contact.on('destroy', this.heading.render, this);
                 }
                 const flyout = this.el.querySelector('.flyout');
@@ -1140,7 +1140,7 @@ converse.plugins.add('converse-chatview', {
             },
 
             createEmojiPicker () {
-                if (_.isUndefined(_converse.emojipicker)) {
+                if (_converse.emojipicker === undefined) {
                     const storage = _converse.config.get('storage'),
                           id = `converse.emoji-${_converse.bare_jid}`;
                     _converse.emojipicker = new _converse.EmojiPicker({'id': id});
@@ -1160,7 +1160,7 @@ converse.plugins.add('converse-chatview', {
             },
 
             toggleEmojiMenu (ev) {
-                if (_.isUndefined(this.emoji_dropdown)) {
+                if (this.emoji_dropdown === undefined) {
                     ev.stopPropagation();
                     this.createEmojiPicker();
                     this.insertEmojiPicker();
@@ -1383,7 +1383,7 @@ converse.plugins.add('converse-chatview', {
 
             _scrollDown () {
                 /* Inner method that gets debounced */
-                if (_.isUndefined(this.content)) {
+                if (this.content === undefined) {
                     return;
                 }
                 if (u.isVisible(this.content) && !this.model.get('scrolled')) {
@@ -1461,7 +1461,7 @@ converse.plugins.add('converse-chatview', {
                   * _converse.api.chatviews.get(['buddy1@example.com', 'buddy2@example.com'])
                   */
                 'get' (jids) {
-                    if (_.isUndefined(jids)) {
+                    if (jids === undefined) {
                         _converse.log(
                             "chatviews.get: You need to provide at least one JID",
                             Strophe.LogLevel.ERROR

src/converse-controlbox.js

@@ -186,7 +186,7 @@ converse.plugins.add('converse-controlbox', {
             },
 
             initialize () {
-                if (_.isUndefined(_converse.controlboxtoggle)) {
+                if (_converse.controlboxtoggle === undefined) {
                     _converse.controlboxtoggle = new _converse.ControlBoxToggle();
                 }
                 _converse.controlboxtoggle.el.insertAdjacentElement('afterend', this.el);
@@ -214,7 +214,7 @@ converse.plugins.add('converse-controlbox', {
 
             render () {
                 if (this.model.get('connected')) {
-                    if (_.isUndefined(this.model.get('closed'))) {
+                    if (this.model.get('closed') === undefined) {
                         this.model.set('closed', !_converse.show_controlbox_by_default);
                     }
                 }

src/converse-dragresize.js

@@ -153,7 +153,7 @@ converse.plugins.add('converse-dragresize', {
                 const flyout = this.el.querySelector('.box-flyout');
                 const style = window.getComputedStyle(flyout);
 
-                if (_.isUndefined(this.model.get('height'))) {
+                if (this.model.get('height') === undefined) {
                     const height = parseInt(style.height.replace(/px$/, ''), 10);
                     const width = parseInt(style.width.replace(/px$/, ''), 10);
                     this.model.set('height', height);
@@ -313,9 +313,9 @@ converse.plugins.add('converse-dragresize', {
             * default_value. If value is close enough to
             * default_value, then default_value is returned instead.
             */
-            if (_.isUndefined(value)) {
+            if (value === undefined) {
                 return undefined;
-            } else if (_.isUndefined(default_value)) {
+            } else if (default_value === undefined) {
                 return value;
             }
             const resistance = 10;

src/converse-message-view.js

@@ -308,7 +308,7 @@ converse.plugins.add('converse-message-view', {
 
             showMessageVersionsModal (ev) {
                 ev.preventDefault();
-                if (_.isUndefined(this.model.message_versions_modal)) {
+                if (this.model.message_versions_modal === undefined) {
                     this.model.message_versions_modal = new _converse.MessageVersionsModal({'model': this.model});
                 }
                 this.model.message_versions_modal.show(ev);

src/converse-modal.js

@@ -91,7 +91,7 @@ converse.plugins.add('converse-modal', {
                         type = 'alert-warning';
                     }
 
-                    if (_.isUndefined(alert)) {
+                    if (alert === undefined) {
                         const model = new Backbone.Model({
                             'title': title,
                             'messages': messages,

src/converse-muc-views.js

@@ -596,7 +596,7 @@ converse.plugins.add('converse-muc-views', {
 
             showRoomDetailsModal (ev) {
                 ev.preventDefault();
-                if (_.isUndefined(this.model.room_details_modal)) {
+                if (this.model.room_details_modal === undefined) {
                     this.model.room_details_modal = new _converse.RoomDetailsModal({'model': this.model});
                 }
                 this.model.room_details_modal.show(ev);
@@ -1528,14 +1528,14 @@ converse.plugins.add('converse-muc-views', {
             },
 
             showAddRoomModal (ev) {
-                if (_.isUndefined(this.add_room_modal)) {
+                if (this.add_room_modal === undefined) {
                     this.add_room_modal = new _converse.AddChatRoomModal({'model': this.model});
                 }
                 this.add_room_modal.show(ev);
             },
 
             showListRoomsModal(ev) {
-                if (_.isUndefined(this.list_rooms_modal)) {
+                if (this.list_rooms_modal === undefined) {
                     this.list_rooms_modal = new _converse.ListChatRoomsModal({'model': this.model});
                 }
                 this.list_rooms_modal.show(ev);
@@ -1896,7 +1896,7 @@ converse.plugins.add('converse-muc-views', {
         function fetchAndSetMUCDomain (controlboxview) {
             if (controlboxview.model.get('connected')) {
                 if (!controlboxview.roomspanel.model.get('muc_domain')) {
-                    if (_.isUndefined(_converse.muc_domain)) {
+                    if (_converse.muc_domain === undefined) {
                         setMUCDomainFromDisco(controlboxview);
                     } else {
                         setMUCDomain(_converse.muc_domain, controlboxview);
@@ -2001,7 +2001,7 @@ converse.plugins.add('converse-muc-views', {
                  */
                 'close' (jids) {
                     let views;
-                    if (_.isUndefined(jids)) {
+                    if (jids === undefined) {
                         views = _converse.chatboxviews;
                     } else if (_.isString(jids)) {
                         views = [_converse.chatboxviews.get(jids)].filter(v => v);

src/converse-notification.js

@@ -111,7 +111,7 @@ converse.plugins.add('converse-notification', {
             // XXX Eventually this can be refactored to use Notification's sound
             // feature, but no browser currently supports it.
             // https://developer.mozilla.org/en-US/docs/Web/API/notification/sound
-            if (_converse.play_sounds && !_.isUndefined(window.Audio)) {
+            if (_converse.play_sounds && window.Audio !== undefined) {
                 const audioOgg = new Audio(_converse.sounds_path+"msg_received.ogg");
                 const canPlayOgg = audioOgg.canPlayType('audio/ogg');
                 if (canPlayOgg === 'probably') {
@@ -157,14 +157,14 @@ converse.plugins.add('converse-notification', {
             } else if (message.getAttribute('type') === 'groupchat') {
                 title = __("%1$s says", Strophe.getResourceFromJid(full_from_jid));
             } else {
-                if (_.isUndefined(_converse.roster)) {
+                if (_converse.roster === undefined) {
                     _converse.log(
                         "Could not send notification, because roster is undefined",
                         Strophe.LogLevel.ERROR);
                     return;
                 }
                 roster_item = _converse.roster.get(from_jid);
-                if (!_.isUndefined(roster_item)) {
+                if (roster_item !== undefined) {
                     title = __("%1$s says", roster_item.getDisplayName());
                 } else {
                     if (_converse.allow_non_roster_messaging) {

src/converse-oauth.js

@@ -42,7 +42,7 @@ converse.plugins.add("converse-oauth", {
 
             insertOAuthProviders () {
                 const { _converse } = this.__super__;
-                if (_.isUndefined(this.oauth_providers_view)) {
+                if (this.oauth_providers_view === undefined) {
                     this.oauth_providers_view =
                         new _converse.OAuthProvidersView({'model': _converse.oauth_providers});
 

src/converse-omemo.js

@@ -902,7 +902,7 @@ converse.plugins.add('converse-omemo', {
             },
 
             fetchSession () {
-                if (_.isUndefined(this._setup_promise)) {
+                if (this._setup_promise === undefined) {
                     this._setup_promise = new Promise((resolve, reject) => {
                         this.fetch({
                             'success': () => {
@@ -1012,7 +1012,7 @@ converse.plugins.add('converse-omemo', {
             },
 
             fetchDevices () {
-                if (_.isUndefined(this._devices_promise)) {
+                if (this._devices_promise === undefined) {
                     this._devices_promise = new Promise(resolve => {
                         this.devices.fetch({
                             'success': _.flow(c => this.onDevicesFound(c), resolve),
@@ -1172,7 +1172,7 @@ converse.plugins.add('converse-omemo', {
         }
 
         function restoreOMEMOSession () {
-            if (_.isUndefined(_converse.omemo_store))  {
+            if (_converse.omemo_store === undefined)  {
                 const storage = _converse.config.get('storage'),
                       id = `converse.omemosession-${_converse.bare_jid}`;
                 _converse.omemo_store = new _converse.OMEMOStore({'id': id});

src/converse-profile.js

@@ -262,21 +262,21 @@ converse.plugins.add('converse-profile', {
             },
 
             showProfileModal (ev) {
-                if (_.isUndefined(this.profile_modal)) {
+                if (this.profile_modal === undefined) {
                     this.profile_modal = new _converse.ProfileModal({model: this.model});
                 }
                 this.profile_modal.show(ev);
             },
 
             showStatusChangeModal (ev) {
-                if (_.isUndefined(this.status_modal)) {
+                if (this.status_modal === undefined) {
                     this.status_modal = new _converse.ChatStatusModal({model: this.model});
                 }
                 this.status_modal.show(ev);
             },
 
             showClientInfoModal(ev) {
-                if (_.isUndefined(this.client_info_modal)) {
+                if (this.client_info_modal === undefined) {
                     this.client_info_modal = new _converse.ClientInfoModal({model: this.model});
                 }
                 this.client_info_modal.show(ev);

src/converse-register.js

@@ -90,7 +90,7 @@ converse.plugins.add('converse-register', {
         Object.assign(_converse.LoginPanel.prototype, {
 
             insertRegisterLink () {
-                if (_.isUndefined(this.registerlinkview)) {
+                if (this.registerlinkview === undefined) {
                     this.registerlinkview = new _converse.RegisterLinkView({'model': this.model});
                     this.registerlinkview.render();
                     const buttons = this.el.querySelector('.buttons');

src/converse-roomslist.js

@@ -135,7 +135,7 @@ converse.plugins.add('converse-roomslist', {
             showRoomDetailsModal (ev) {
                 const room = _converse.chatboxes.get(this.model.get('jid'));
                 ev.preventDefault();
-                if (_.isUndefined(room.room_details_modal)) {
+                if (room.room_details_modal === undefined) {
                     room.room_details_modal = new _converse.RoomDetailsModal({'model': room});
                 }
                 room.room_details_modal.show(ev);
@@ -199,7 +199,7 @@ converse.plugins.add('converse-roomslist', {
 
             insertIntoControlBox () {
                 const controlboxview = _converse.chatboxviews.get('controlbox');
-                if (!_.isUndefined(controlboxview) && !u.rootContains(_converse.root, this.el)) {
+                if (controlboxview !== undefined && !u.rootContains(_converse.root, this.el)) {
                     const el = controlboxview.el.querySelector('.open-rooms-list');
                     if (!_.isNull(el)) {
                         el.parentNode.replaceChild(this.el, el);

src/converse-rosterview.js

@@ -784,7 +784,7 @@ converse.plugins.add('converse-rosterview', {
             },
 
             showAddContactModal (ev) {
-                if (_.isUndefined(this.add_contact_modal)) {
+                if (this.add_contact_modal === undefined) {
                     this.add_contact_modal = new _converse.AddContactModal({'model': new Backbone.Model()});
                 }
                 this.add_contact_modal.show(ev);
@@ -944,7 +944,7 @@ converse.plugins.add('converse-rosterview', {
         _converse.api.listen.on('chatBoxesInitialized', () => {
             function highlightRosterItem (chatbox) {
                 const contact = _converse.roster.findWhere({'jid': chatbox.get('jid')});
-                if (!_.isUndefined(contact)) {
+                if (contact !== undefined) {
                     contact.trigger('highlight');
                 }
             }

src/headless/converse-bookmarks.js

@@ -192,14 +192,14 @@ converse.plugins.add('converse-bookmarks', {
 
             markRoomAsBookmarked (bookmark) {
                 const groupchat = _converse.chatboxes.get(bookmark.get('jid'));
-                if (!_.isUndefined(groupchat)) {
+                if (groupchat !== undefined) {
                     groupchat.save('bookmarked', true);
                 }
             },
 
             markRoomAsUnbookmarked (bookmark) {
                 const groupchat = _converse.chatboxes.get(bookmark.get('jid'));
-                if (!_.isUndefined(groupchat)) {
+                if (groupchat !== undefined) {
                     groupchat.save('bookmarked', false);
                 }
             },
@@ -222,7 +222,7 @@ converse.plugins.add('converse-bookmarks', {
 
             onBookmarksReceived (deferred, iq) {
                 this.createBookmarksFromStanza(iq);
-                if (!_.isUndefined(deferred)) {
+                if (deferred !== undefined) {
                     return deferred.resolve();
                 }
             },
@@ -276,7 +276,7 @@ converse.plugins.add('converse-bookmarks', {
         }
 
         _converse.api.listen.on('clearSession', () => {
-            if (!_.isUndefined(_converse.bookmarks)) {
+            if (_converse.bookmarks !== undefined) {
                 _converse.bookmarks.reset();
                 _converse.bookmarks.browserStorage._clear();
                 window.sessionStorage.removeItem(_converse.bookmarks.fetched_flag);

src/headless/converse-chatboxes.js

@@ -415,7 +415,7 @@ converse.plugins.add('converse-chatboxes', {
              * @param { string } state - The chat state (consts ACTIVE, COMPOSING, PAUSED, INACTIVE, GONE)
              */
             setChatState (state, options) {
-                if (!_.isUndefined(this.chat_state_timeout)) {
+                if (this.chat_state_timeout !== undefined) {
                     window.clearTimeout(this.chat_state_timeout);
                     delete this.chat_state_timeout;
                 }
@@ -611,7 +611,7 @@ converse.plugins.add('converse-chatboxes', {
             },
 
             handleReceipt (stanza, from_jid, is_carbon, is_me, is_mam) {
-                const requests_receipt = !_.isUndefined(sizzle(`request[xmlns="${Strophe.NS.RECEIPTS}"]`, stanza).pop());
+                const requests_receipt = sizzle(`request[xmlns="${Strophe.NS.RECEIPTS}"]`, stanza).pop() !== undefined;
                 if (requests_receipt && !is_carbon && !is_me) {
                     this.sendReceiptStanza(from_jid, stanza.getAttribute('id'));
                 }
@@ -1112,7 +1112,7 @@ converse.plugins.add('converse-chatboxes', {
                 }
                 const contact_jid = is_me ? Strophe.getBareJidFromJid(to_jid) : from_bare_jid;
                 const contact = await _converse.api.contacts.get(contact_jid);
-                const is_roster_contact = !_.isUndefined(contact);
+                const is_roster_contact = contact !== undefined;
                 if (!is_me && !is_roster_contact && !_converse.allow_non_roster_messaging) {
                     return;
                 }
@@ -1365,7 +1365,7 @@ converse.plugins.add('converse-chatboxes', {
                  *
                  */
                 get (jids) {
-                    if (_.isUndefined(jids)) {
+                    if (jids === undefined) {
                         const result = [];
                         _converse.chatboxes.each(function (chatbox) {
                             // FIXME: Leaky abstraction from MUC. We need to add a

src/headless/converse-core.js

@@ -291,7 +291,7 @@ Strophe.error = function (msg) { _converse.log(msg, Strophe.LogLevel.ERROR); };
  * @param { String } str - The string to translate
  */
 _converse.__ = function (str) {
-    if (_.isUndefined(i18n)) {
+    if (i18n === undefined) {
         return str;
     }
     return i18n.translate.apply(i18n, arguments);
@@ -505,7 +505,7 @@ const debouncedReconnect = _.debounce(reconnect, 2000);
 
 
 function clearSession  () {
-    if (!_.isUndefined(_converse.session)) {
+    if (_converse.session !== undefined) {
         _converse.session.destroy();
         delete _converse.session;
     }
@@ -740,10 +740,10 @@ function cleanup () {
 
 
 _converse.initialize = async function (settings, callback) {
-    settings = !_.isUndefined(settings) ? settings : {};
+    settings = settings !== undefined ? settings : {};
     const init_promise = u.getResolveablePromise();
     PROMISES.forEach(addPromise);
-    if (!_.isUndefined(_converse.connection)) {
+    if (_converse.connection !== undefined) {
         cleanup();
     }
 
@@ -782,7 +782,7 @@ _converse.initialize = async function (settings, callback) {
     });
 
     /* Localisation */
-    if (!_.isUndefined(i18n)) {
+    if (i18n !== undefined) {
         i18n.setLocales(settings.i18n, _converse);
     } else {
         _converse.locale = 'en';
@@ -977,7 +977,7 @@ _converse.initialize = async function (settings, callback) {
                 return _converse.finishDisconnection();
             }
         } else if (_converse.disconnection_cause === _converse.LOGOUT ||
-                (!_.isUndefined(reason) && reason === _.get(Strophe, 'ErrorCondition.NO_AUTH_MECH')) ||
+                (reason !== undefined && reason === _.get(Strophe, 'ErrorCondition.NO_AUTH_MECH')) ||
                 reason === "host-unknown" ||
                 reason === "remote-connection-failed" ||
                 !_converse.auto_reconnect) {
@@ -991,10 +991,10 @@ _converse.initialize = async function (settings, callback) {
         /* Used to keep track of why we got disconnected, so that we can
          * decide on what the next appropriate action is (in onDisconnected)
          */
-        if (_.isUndefined(cause)) {
+        if (cause === undefined) {
             delete _converse.disconnection_cause;
             delete _converse.disconnection_reason;
-        } else if (_.isUndefined(_converse.disconnection_cause) || override) {
+        } else if (_converse.disconnection_cause === undefined || override) {
             _converse.disconnection_cause = cause;
             _converse.disconnection_reason = reason;
         }
@@ -1049,7 +1049,7 @@ _converse.initialize = async function (settings, callback) {
             if (message === "host-unknown" || message == "remote-connection-failed") {
                 feedback = __("Sorry, we could not connect to the XMPP host with domain: %1$s",
                     `\"${Strophe.getDomainFromJid(_converse.connection.jid)}\"`);
-            } else if (!_.isUndefined(message) && message === _.get(Strophe, 'ErrorCondition.NO_AUTH_MECH')) {
+            } else if (message !== undefined && message === _.get(Strophe, 'ErrorCondition.NO_AUTH_MECH')) {
                 feedback = __("The XMPP server did not offer a supported authentication mechanism");
             }
             _converse.setConnectionStatus(status, feedback);
@@ -1087,7 +1087,7 @@ _converse.initialize = async function (settings, callback) {
     this.initStatus = (reconnecting) => {
         // If there's no xmppstatus obj, then we were never connected to
         // begin with, so we set reconnecting to false.
-        reconnecting = _.isUndefined(_converse.xmppstatus) ? false : reconnecting;
+        reconnecting = _converse.xmppstatus === undefined ? false : reconnecting;
         if (reconnecting) {
             _converse.onStatusInitialized(reconnecting);
         } else {
@@ -1306,7 +1306,7 @@ _converse.initialize = async function (settings, callback) {
     if (_converse.isTestEnv()) {
         await finishInitialization();
         return _converse;
-    } else if (!_.isUndefined(i18n)) {
+    } else if (i18n !== undefined) {
         const url = u.interpolate(_converse.locales_url, {'locale': _converse.locale});
         try {
             await i18n.fetchTranslations(_converse.locale, _converse.locales, url);
@@ -1457,7 +1457,7 @@ _converse.api = {
             _converse.trigger.apply(_converse, arguments);
         }
         const promise = _converse.promises[name];
-        if (!_.isUndefined(promise)) {
+        if (promise !== undefined) {
             promise.resolve();
         }
     },
@@ -1517,7 +1517,7 @@ _converse.api = {
         logout () {
             clearSession();
             _converse.setDisconnectionCause(_converse.LOGOUT, undefined, true);
-            if (!_.isUndefined(_converse.connection)) {
+            if (_converse.connection !== undefined) {
                 _converse.connection.disconnect();
             } else {
                 tearDown();
@@ -1804,7 +1804,7 @@ _converse.api = {
             return u.waitUntil(condition);
         } else {
             const promise = _converse.promises[condition];
-            if (_.isUndefined(promise)) {
+            if (promise === undefined) {
                 return null;
             }
             return promise;
@@ -1914,7 +1914,7 @@ const converse = {
          */
         add (name, plugin) {
             plugin.__name__ = name;
-            if (!_.isUndefined(_converse.pluggable.plugins[name])) {
+            if (_converse.pluggable.plugins[name] !== undefined) {
                 throw new TypeError(
                     `Error: plugin with name "${name}" has already been ` + 'registered!'
                 );

src/headless/converse-disco.js

@@ -161,7 +161,7 @@ converse.plugins.add('converse-disco', {
                         return;
                     }
                     const jid = item.getAttribute('jid');
-                    if (_.isUndefined(this.items.get(jid))) {
+                    if (this.items.get(jid) === undefined) {
                         const entity = _converse.disco_entities.get(jid);
                         if (entity) {
                             this.items.add(entity);

src/headless/converse-mam.js

@@ -200,7 +200,7 @@ converse.plugins.add('converse-mam', {
         /************************ BEGIN Event Handlers ************************/
         function getMAMPrefsFromFeature (feature) {
             const prefs = feature.get('preferences') || {};
-            if (feature.get('var') !== Strophe.NS.MAM || _.isUndefined(_converse.message_archiving)) {
+            if (feature.get('var') !== Strophe.NS.MAM || _converse.message_archiving === undefined) {
                 return;
             }
             if (prefs['default'] !== _converse.message_archiving) {

src/headless/converse-muc.js

@@ -862,7 +862,7 @@ converse.plugins.add('converse-muc', {
              * @returns { Promise } A promise which resolves and fails depending on the XMPP server response.
              */
             setAffiliation (affiliation, members) {
-                members = members.filter(m => _.isUndefined(m.affiliation) || m.affiliation === affiliation);
+                members = members.filter(m => m.affiliation === undefined || m.affiliation === affiliation);
                 return Promise.all(members.map(m => this.sendAffiliationIQ(affiliation, m)));
             },
 
@@ -1039,7 +1039,7 @@ converse.plugins.add('converse-muc', {
                         'nick': member.nick,
                         'jid': member.jid
                     });
-                if (!_.isUndefined(member.reason)) {
+                if (member.reason !== undefined) {
                     iq.c("reason", member.reason);
                 }
                 return _converse.api.sendIQ(iq);
@@ -1917,8 +1917,8 @@ converse.plugins.add('converse-muc', {
 
             async fetchMembers () {
                 const new_members = await this.chatroom.getJidsWithAffiliations(['member', 'owner', 'admin']);
-                const new_jids = new_members.map(m => m.jid).filter(m => !_.isUndefined(m));
-                const new_nicks = new_members.map(m => !m.jid && m.nick || undefined).filter(m => !_.isUndefined(m));
+                const new_jids = new_members.map(m => m.jid).filter(m => m !== undefined);
+                const new_nicks = new_members.map(m => !m.jid && m.nick || undefined).filter(m => m !== undefined);
                 const removed_members = this.filter(m => {
                         return ['admin', 'member', 'owner'].includes(m.get('affiliation')) &&
                             !new_nicks.includes(m.get('nick')) &&
@@ -2148,13 +2148,13 @@ converse.plugins.add('converse-muc', {
                  */
                 create (jids, attrs={}) {
                     attrs = _.isString(attrs) ? {'nick': attrs} : (attrs || {});
-                    if (_.isUndefined(attrs.maximize)) {
+                    if (attrs.maximize === undefined) {
                         attrs.maximize = false;
                     }
                     if (!attrs.nick && _converse.muc_nickname_from_jid) {
                         attrs.nick = Strophe.getNodeFromJid(_converse.bare_jid);
                     }
-                    if (_.isUndefined(jids)) {
+                    if (jids === undefined) {
                         throw new TypeError('rooms.create: You need to provide at least one JID');
                     } else if (_.isString(jids)) {
                         return createChatRoom(jids, attrs);
@@ -2223,7 +2223,7 @@ converse.plugins.add('converse-muc', {
                  */
                 async open (jids, attrs, force=false) {
                     await _converse.api.waitUntil('chatBoxesFetched');
-                    if (_.isUndefined(jids)) {
+                    if (jids === undefined) {
                         const err_msg = 'rooms.open: You need to provide at least one JID';
                         _converse.log(err_msg, Strophe.LogLevel.ERROR);
                         throw(new TypeError(err_msg));
@@ -2264,10 +2264,10 @@ converse.plugins.add('converse-muc', {
                 get (jids, attrs, create) {
                     if (_.isString(attrs)) {
                         attrs = {'nick': attrs};
-                    } else if (_.isUndefined(attrs)) {
+                    } else if (attrs === undefined) {
                         attrs = {};
                     }
-                    if (_.isUndefined(jids)) {
+                    if (jids === undefined) {
                         const result = [];
                         _converse.chatboxes.each(function (chatbox) {
                             if (chatbox.get('type') === _converse.CHATROOMS_TYPE) {

src/headless/converse-ping.js

@@ -40,9 +40,9 @@ converse.plugins.add('converse-ping', {
             if (_.isNil(jid)) {
                 jid = Strophe.getDomainFromJid(_converse.bare_jid);
             }
-            if (_.isUndefined(timeout) ) { timeout = null; }
-            if (_.isUndefined(success) ) { success = null; }
-            if (_.isUndefined(error) ) { error = null; }
+            if (timeout === undefined ) { timeout = null; }
+            if (success === undefined ) { success = null; }
+            if (error === undefined ) { error = null; }
             if (_converse.connection) {
                 const id = _converse.connection.getUniqueId('ping');
                 const iq = $iq({
@@ -66,7 +66,7 @@ converse.plugins.add('converse-ping', {
         };
 
         _converse.registerPongHandler = function () {
-            if (!_.isUndefined(_converse.connection.disco)) {
+            if (_converse.connection.disco !== undefined) {
                 _converse.api.disco.own.features.add(Strophe.NS.PING);
             }
             return _converse.connection.addHandler(_converse.pong, Strophe.NS.PING, "iq", "get");

src/headless/converse-roster.js

@@ -907,7 +907,7 @@ converse.plugins.add('converse-roster', {
         });
 
         _converse.unregisterPresenceHandler = function () {
-            if (!_.isUndefined(_converse.presence_ref)) {
+            if (_converse.presence_ref !== undefined) {
                 _converse.connection.deleteHandler(_converse.presence_ref);
                 delete _converse.presence_ref;
             }
@@ -917,7 +917,7 @@ converse.plugins.add('converse-roster', {
         /********** Event Handlers *************/
         function updateUnreadCounter (chatbox) {
             const contact = _converse.roster.findWhere({'jid': chatbox.get('jid')});
-            if (!_.isUndefined(contact)) {
+            if (contact !== undefined) {
                 contact.save({'num_unread': chatbox.get('num_unread')});
             }
         }
@@ -949,7 +949,7 @@ converse.plugins.add('converse-roster', {
         _converse.api.listen.on('afterTearDown', () => {
             if (_converse.presences) {
                 _converse.presences.each(p => {
-                    _.each(p.resources.reject(_.isUndefined), r => r.destroy({'silent': true}));
+                    p.resources.reject(r => r === undefined).forEach(r => r.destroy({'silent': true}));
                     p.save({'show': 'offline'}, {'silent': true})
                 });
             }
@@ -1049,7 +1049,7 @@ converse.plugins.add('converse-roster', {
                 async get (jids) {
                     await _converse.api.waitUntil('rosterContactsFetched');
                     const _getter = jid => _converse.roster.get(Strophe.getBareJidFromJid(jid));
-                    if (_.isUndefined(jids)) {
+                    if (jids === undefined) {
                         jids = _converse.roster.pluck('jid');
                     } else if (_.isString(jids)) {
                         return _getter(jids);

src/headless/utils/core.js

@@ -173,7 +173,7 @@ u.applyUserSettings = function applyUserSettings (context, settings, user_settin
      * add settings which are whitelisted.
      */
     for (var k in settings) {
-        if (_.isUndefined(user_settings[k])) {
+        if (user_settings[k] === undefined) {
             continue;
         }
         if (_.isObject(settings[k]) && !Array.isArray(settings[k])) {

src/headless/utils/emoji.js

@@ -204,7 +204,7 @@ u.getEmojisByCategory = function (_converse) {
     /* Return a dict of emojis with the categories as keys and
      * lists of emojis in that category as values.
      */
-    if (_.isUndefined(_converse.emojis_by_category)) {
+    if (_converse.emojis_by_category === undefined) {
         const emojis = Object.values(_.mapValues(emoji_list, function (value, key, o) {
             value._shortname = key;
             return value