diff --git a/client/src/ajax.js b/client/src/ajax.js
index 02d3f9d9b6..75d66ed26a 100644
--- a/client/src/ajax.js
+++ b/client/src/ajax.js
@@ -43,6 +43,7 @@ define('ajax', [], function () {
          *
          * @property {Number} [timeout] A timeout.
          * @property {Object.<string,string>} [headers] A request headers.
+         * @property {'xml'|'json'|'text'} [dataType] A data type.
          */
 
         /**
diff --git a/client/src/collection.js b/client/src/collection.js
index fa67d49096..6a893678a7 100644
--- a/client/src/collection.js
+++ b/client/src/collection.js
@@ -181,9 +181,11 @@ define('collection', [], function () {
         _user: null,
 
         /**
+         * Initialize.
+         *
          * @protected
-         * @param {module:model.Class[]} models
-         * @param {Object} options
+         * @param {module:model.Class[]} models Models.
+         * @param {Object} options Options.
          */
         initialize: function (models, options) {
             options = options || {};
@@ -305,7 +307,14 @@ define('collection', [], function () {
             this.fetch();
         },
 
-        parse: function (response) {
+        /**
+         * Parse a response from the backend.
+         *
+         * @param {Object} response A response.
+         * @param {Object} options Options.
+         * @returns {module:collection.Class[]}
+         */
+        parse: function (response, options) {
             this.total = response.total;
 
             if ('additionalData' in response) {
diff --git a/client/src/metadata.js b/client/src/metadata.js
index 421391e6ad..bba3db667f 100644
--- a/client/src/metadata.js
+++ b/client/src/metadata.js
@@ -28,21 +28,43 @@
 
 define('metadata', [], function () {
 
+    /**
+     * Application metadata.
+     *
+     * @class
+     * @name Class
+     * @memberOf module:metadata
+     *
+     * @param {module:cache.Class} [cache] A cache.
+     */
     let Metadata = function (cache) {
+        /**
+         * @private
+         * @type {module:cache.Class|null}
+         */
         this.cache = cache || null;
 
+        /**
+         * @private
+         * @type {Object}
+         */
         this.data = {};
-        this.ajax = $.ajax;
     };
 
-    _.extend(Metadata.prototype, {
-
-        cache: null,
-
-        data: null,
+    _.extend(Metadata.prototype, /** @lends module:metadata.Class# */{
 
+        /**
+         * @private
+         */
         url: 'Metadata',
 
+        /**
+         * Load from cache or the backend (if not yet cached).
+         *
+         * @param {Function|null} [callback] Deprecated. Use a promise.
+         * @param {boolean} [disableCache=false] Bypass cache.
+         * @returns {Promise}
+         */
         load: function (callback, disableCache) {
             this.off('sync');
 
@@ -64,25 +86,38 @@ define('metadata', [], function () {
             });
         },
 
+        /**
+         * Load from the server.
+         *
+         * @returns {Promise}
+         */
         loadSkipCache: function () {
             return this.load(null, true);
         },
 
+        /**
+         * @private
+         * @returns {Promise}
+         */
         fetch: function () {
-            return this.ajax({
-                url: this.url,
-                type: 'GET',
-                dataType: 'JSON',
-                success: data => {
-                    this.data = data;
-
-                    this.storeToCache();
-
-                    this.trigger('sync');
-                },
-            });
+            return Espo.Ajax
+                .getRequest(this.url, null, {
+                    dataType: 'json',
+                    success: data => {
+                        this.data = data;
+                        this.storeToCache();
+                        this.trigger('sync');
+                    },
+                });
         },
 
+        /**
+         * Get a value.
+         *
+         * @param {string[]|string} path A key path.
+         * @param {*} [defaultValue] A value to return if not set.
+         * @returns {*} Null if not set.
+         */
         get: function (path, defaultValue) {
             defaultValue = defaultValue || null;
 
@@ -117,6 +152,10 @@ define('metadata', [], function () {
             return result;
         },
 
+        /**
+         * @private
+         * @returns {boolean} True if success.
+         */
         loadFromCache: function () {
             if (this.cache) {
                 let cached = this.cache.get('app', 'metadata');
@@ -131,12 +170,18 @@ define('metadata', [], function () {
             return null;
         },
 
+        /**
+         * @private
+         */
         storeToCache: function () {
             if (this.cache) {
                 this.cache.set('app', 'metadata', this.data);
             }
         },
 
+        /**
+         * Clear cache.
+         */
         clearCache: function () {
             if (!this.cache) {
                 return;
@@ -145,6 +190,11 @@ define('metadata', [], function () {
             this.cache.clear('app', 'metadata');
         },
 
+        /**
+         * Get a scope list.
+         *
+         * @returns {string}
+         */
         getScopeList: function () {
             let scopes = this.get('scopes') || {};
             let scopeList = [];
@@ -162,6 +212,11 @@ define('metadata', [], function () {
             return scopeList;
         },
 
+        /**
+         * Get an object-scope list. An object-scope represents a business entity.
+         *
+         * @returns {string[]}
+         */
         getScopeObjectList: function () {
             let scopes = this.get('scopes') || {};
             let scopeList = [];
@@ -183,6 +238,11 @@ define('metadata', [], function () {
             return scopeList;
         },
 
+        /**
+         * Get an entity-scope list. Scopes that represents entities.
+         *
+         * @returns {string[]}
+         */
         getScopeEntityList: function () {
             var scopes = this.get('scopes') || {};
             var scopeList = [];
diff --git a/client/src/model-offline.js b/client/src/model-offline.js
index f0e2d8efdc..697af01be8 100644
--- a/client/src/model-offline.js
+++ b/client/src/model-offline.js
@@ -26,14 +26,17 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-/**
- * @internal Not used.
- */
-define('model-offline', 'model', function (Model) {
+define('model-offline', ['model'], function (Model) {
 
-    let ModelOffline = Model.extend({
-
-        name: null,
+    /**
+     * @internal Not used.
+     *
+     * @class
+     * @name Class
+     * @extends module:model.Class
+     * @memberOf module:model-offline
+     */
+    return Model.extend(/** @lends module:model-offline.Class# */{
 
         cache: null,
 
@@ -97,8 +100,5 @@ define('model-offline', 'model', function (Model) {
         isNew: function () {
             return false;
         },
-
     });
-
-    return ModelOffline;
 });
diff --git a/client/src/model.js b/client/src/model.js
index bf71d4ac92..042ca0739c 100644
--- a/client/src/model.js
+++ b/client/src/model.js
@@ -156,6 +156,8 @@ define('model', [], function () {
         defs: null,
 
         /**
+         * Initialize.
+         *
          * @protected
          */
         initialize: function () {
diff --git a/client/src/multi-collection.js b/client/src/multi-collection.js
index e7fa99ecd7..a0f9b73b0e 100644
--- a/client/src/multi-collection.js
+++ b/client/src/multi-collection.js
@@ -28,21 +28,35 @@
 
 define('multi-collection', ['collection'], function (Collection) {
 
-    let MultiCollection = Collection.extend({
+    /**
+     * A collection that can contain entities of different entity types.
+     *
+     * @class
+     * @name Class
+     * @extends module:collection.Class
+     * @memberOf module:multi-collection
+     */
+    return Collection.extend(/** @lends module:multi-collection.Class# */{
 
         /**
-         * @prop {Object} seeds Hash off model classes.
+         * @private
          */
         seeds: null,
 
+        /**
+         * @inheritDoc
+         */
         initialize: function (models, options) {
             options = options || {};
 
             this.data = {};
 
-            Backbone.Collection.prototype.initialize.call(this);
+            Backbone.Collection.prototype.initialize.call(this, options);
         },
 
+        /**
+         * @inheritDoc
+         */
         parse: function (resp, options) {
             this.total = resp.total;
 
@@ -54,8 +68,5 @@ define('multi-collection', ['collection'], function (Collection) {
                 return new this.seeds[attributes._scope](a, options);
             });
         },
-
     });
-
-    return MultiCollection;
 });
diff --git a/client/src/namespace.js b/client/src/namespace.js
index 1685952293..41522be5c5 100644
--- a/client/src/namespace.js
+++ b/client/src/namespace.js
@@ -26,4 +26,4 @@
  * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
  ************************************************************************/
 
-var Espo = {};
+let Espo = {};
diff --git a/client/src/number.js b/client/src/number.js
index 027faf629c..67347d50ec 100644
--- a/client/src/number.js
+++ b/client/src/number.js
@@ -151,7 +151,6 @@ define('number', [], function () {
 
             return decimalMark;
         },
-
     });
 
     return NumberUtil;
diff --git a/client/src/page-title.js b/client/src/page-title.js
index 8436c6c055..75db96b92e 100644
--- a/client/src/page-title.js
+++ b/client/src/page-title.js
@@ -66,7 +66,6 @@ define('page-title', [], function () {
 
             $('head title').text(value);
         },
-
     });
 
     return PageTitle;
diff --git a/client/src/session-storage.js b/client/src/session-storage.js
index 36d80a47aa..cd1a541016 100644
--- a/client/src/session-storage.js
+++ b/client/src/session-storage.js
@@ -86,6 +86,5 @@ define('session-storage', ['storage'], function (Dep) {
                 }
             }
         },
-
     });
 });