diff --git a/core/misc/drupal.js b/core/misc/drupal.js
index 75f85bb..b1b4cc8 100644
--- a/core/misc/drupal.js
+++ b/core/misc/drupal.js
@@ -6,14 +6,20 @@
 /**
  * A jQuery object.
  *
+ * HTMLElement or collection of HTMLElement held by a jQuery object.
+ *
  * @typedef {object} jQuery
  *
  * @prop {number} length=0
+ *   Number of HTMLElement contained in the jQuery object.
  */
 
 /**
  * Variable generated by Drupal with all the configuration created from PHP.
  *
+ * This variable is used to pass data from the backend to the frontend. Data
+ * contained in `drupalSettings` is used during behavior initialization.
+ *
  * @global
  *
  * @var {object} drupalSettings
@@ -22,6 +28,9 @@
 /**
  * Variable generated by Drupal that holds all translated strings from PHP.
  *
+ * Content of this variable is automatically created by Drupal when using locale
+ * module. It holds the translation of strings used on the page.
+ *
  * @global
  *
  * @var {object} drupalTranslations
@@ -30,6 +39,8 @@
 /**
  * Global Drupal object.
  *
+ * All Drupal JS API is contained in this namespace.
+ *
  * @global
  *
  * @namespace
@@ -51,8 +62,7 @@ if (window.jQuery) {
   "use strict";
 
   /**
-   * Custom error type thrown after attach/detach if one or more behaviors
-   * failed.
+   * Custom error thrown after attach/detach if one or more behaviors failed.
    *
    * @memberof Drupal
    *
@@ -70,21 +80,21 @@ if (window.jQuery) {
   function DrupalBehaviorError(list, event) {
 
     /**
-     * Setting name helps debuggers.
+     * Setting the name property helps debuggers display a user-friendly type.
      *
      * @type {string}
      */
     this.name = 'DrupalBehaviorError';
 
     /**
-     * Execution phase errors were triggered.
+     * Execution phase during which behavior errors were triggered.
      *
      * @type {string}
      */
     this.event = event || 'attach';
 
     /**
-     * All thrown errors.
+     * Complete list of all thrown errors.
      *
      * @type {Array.<Error>}
      */
@@ -98,7 +108,7 @@ if (window.jQuery) {
     }
 
     /**
-     * Final message to send to debuggers.
+     * Final message that will be displayed in browser's console/debugger.
      *
      * @type {string}
      */
@@ -112,8 +122,10 @@ if (window.jQuery) {
    *
    * @callback Drupal~behaviorAttach
    *
-   * @param {HTMLElement} context
+   * @param {HTMLDocument|HTMLElement} context
+   *   An element to attach behaviors to.
    * @param {object} settings
+   *   An object containing settings for the current context.
    *
    * @see Drupal.attachBehaviors
    */
@@ -123,10 +135,12 @@ if (window.jQuery) {
    *
    * @callback Drupal~behaviorDetach
    *
-   * @param {HTMLElement} context
-   * @param {object} settings
+   * @param {HTMLDocument|HTMLElement} context
+   *   An element to detach behaviors from.
+   * @param {?object} settings
+   *   An object containing settings for the current context. It is rarely used.
    * @param {string} trigger
-   *   One of 'unload', 'serialize' or 'move'.
+   *   One of `unload`, `move` or `serialize`.
    *
    * @see Drupal.detachBehaviors
    */
@@ -135,7 +149,7 @@ if (window.jQuery) {
    * @typedef {object} Drupal~behavior
    *
    * @prop {Drupal~behaviorAttach} attach
-   *   Function run on page load and after an AJAX call.
+   *   Function run on page load and after an Ajax call.
    * @prop {Drupal~behaviorDetach} detach
    *   Function run when content is serialized or removed from the page.
    */
@@ -154,7 +168,7 @@ if (window.jQuery) {
    * Behaviors are event-triggered actions that attach to page elements,
    * enhancing default non-JavaScript UIs. Behaviors are registered in the
    * {@link Drupal.behaviors} object using the method 'attach' and optionally
-   * also 'detach' as follows:
+   * also 'detach'.
    *
    * {@link Drupal.attachBehaviors} is added below to the jQuery.ready event and
    * therefore runs on initial page load. Developers implementing Ajax in their
@@ -172,19 +186,18 @@ if (window.jQuery) {
    * @example
    * Drupal.behaviors.behaviorName = {
    *   attach: function (context, settings) {
-   *     ...
+   *     // ...
    *   },
    *   detach: function (context, settings, trigger) {
-   *     ...
+   *     // ...
    *   }
    * };
    *
-   * @param {Element} context
-   *   An element to attach behaviors to. If none is given, the document
-   *   element is used.
-   * @param {object} settings
+   * @param {HTMLDocument|HTMLElement} [context=document]
+   *   An element to attach behaviors to.
+   * @param {object} [settings=drupalSettings]
    *   An object containing settings for the current context. If none is given,
-   *   the global drupalSettings object is used.
+   *   the global {@link drupalSettings} object is used.
    *
    * @see Drupal~behaviorAttach
    * @see Drupal.detachBehaviors
@@ -230,17 +243,16 @@ if (window.jQuery) {
    * implementation, i.e. .removeOnce('behaviorName'), to ensure the behavior
    * is detached only from previously processed elements.
    *
-   * @param {Element} context
-   *   An element to detach behaviors from. If none is given, the document
-   *   element is used.
-   * @param {object} settings
+   * @param {HTMLDocument|HTMLElement} [context=document]
+   *   An element to detach behaviors from.
+   * @param {object} [settings=drupalSettings]
    *   An object containing settings for the current context. If none given,
-   *   the global drupalSettings object is used.
-   * @param {string} trigger
+   *   the global {@link drupalSettings} object is used.
+   * @param {string} [trigger=unload]
    *   A string containing what's causing the behaviors to be detached. The
    *   possible triggers are:
-   *   - unload: (default) The context element is being removed from the DOM.
-   *   - move: The element is about to be moved within the DOM (for example,
+   *   - `unload`: The context element is being removed from the DOM.
+   *   - `move`: The element is about to be moved within the DOM (for example,
    *     during a tabledrag row swap). After the move is completed,
    *     {@link Drupal.attachBehaviors} is called, so that the behavior can undo
    *     whatever it did in response to the move. Many behaviors won't need to
@@ -248,7 +260,7 @@ if (window.jQuery) {
    *     IFRAME elements reload their "src" when being moved within the DOM,
    *     behaviors bound to IFRAME elements (like WYSIWYG editors) may need to
    *     take some action.
-   *   - serialize: When an Ajax form is submitted, this is called with the
+   *   - `serialize`: When an Ajax form is submitted, this is called with the
    *     form as the context. This provides every behavior within the form an
    *     opportunity to ensure that the field elements have correct content
    *     in them before the form is serialized. The canonical use-case is so
@@ -288,8 +300,11 @@ if (window.jQuery) {
    * Helper to test document width for mobile configurations.
    *
    * @param {number} [width=640]
+   *   Value of the width to check for.
    *
    * @return {bool}
+   *   Returns true if the document's `clientWidth` is bigger than `width`,
+   *   returns false otherwise.
    *
    * @deprecated Temporary solution for the mobile initiative.
    */
@@ -327,13 +342,14 @@ if (window.jQuery) {
    *   An object of replacements pairs to make. Incidences of any key in this
    *   array are replaced with the corresponding value. Based on the first
    *   character of the key, the value is escaped and/or themed:
-   *    - !variable: inserted as is
-   *    - @variable: escape plain text to HTML ({@link Drupal.checkPlain})
-   *    - %variable: escape text and theme as a placeholder for user-submitted
+   *    - `!variable`: inserted as is
+   *    - `@variable`: escape plain text to HTML ({@link Drupal.checkPlain})
+   *    - `%variable`: escape text and theme as a placeholder for user-submitted
    *      content ({@link Drupal.checkPlain} +
    *      {@link Drupal.theme}('placeholder'))
    *
    * @return {string}
+   *   Returns the formatted string.
    *
    * @see Drupal.t
    */
@@ -429,11 +445,12 @@ if (window.jQuery) {
    *   of any key in this array are replaced with the corresponding value.
    *   See {@link Drupal.formatString}.
    * @param {object} [options]
+   *   Additional options for translation.
    * @param {string} [options.context='']
    *   The context the source string belongs to.
    *
    * @return {string}
-   *   The translated string.
+   *   Returns the translated string.
    */
   Drupal.t = function (str, args, options) {
     options = options || {};
@@ -457,6 +474,7 @@ if (window.jQuery) {
    *   Drupal path to transform to URL.
    *
    * @return {string}
+   *   Returns the full Drupal URL.
    */
   Drupal.url = function (path) {
     return drupalSettings.path.baseUrl + drupalSettings.path.pathPrefix + path;
@@ -523,6 +541,7 @@ if (window.jQuery) {
    *   Unencoded path.
    *
    * @return {string}
+   *   Returns the encoded path.
    */
   Drupal.encodePath = function (item) {
     return window.encodeURIComponent(item).replace(/%2F/g, '/');