diff --git a/src/wp-admin/js/editor.js b/src/wp-admin/js/editor.js
index e3fbaab945..002cf4a11f 100644
--- a/src/wp-admin/js/editor.js
+++ b/src/wp-admin/js/editor.js
@@ -1,14 +1,45 @@
 
 ( function( $ ) {
+	/**
+	 * @summary Creates the tinyMCE editors.
+	 *
+	 * Creates the tinyMCE editor and binds all events used for switching
+	 * from visual to text mode.
+	 *
+	 * @since 4.3.0
+	 *
+	 * @class
+	 */
 	function SwitchEditors() {
 		var tinymce, $$,
 			exports = {};
 
+		/**
+		 * @summary Initializes the event binding for switching editors.
+		 *
+		 * @since 4.3.0
+		 *
+		 * @returns {void}
+		 */
 		function init() {
 			if ( ! tinymce && window.tinymce ) {
 				tinymce = window.tinymce;
 				$$ = tinymce.$;
 
+				/**
+				 * @summary Handles onclick events for the editor buttons.
+				 *
+				 * @since 4.3.0
+				 *
+				 * Handles an onclick event on the document.
+				 * Switches the editor between visual and text,
+				 * if the clicked element has the 'wp-switch-editor' class.
+				 * If the class name is switch-html switches to the HTML editor,
+				 * if the class name is switch-tmce
+				 * switches to the TMCE editor.
+				 *
+				 * @returns {void}
+				 */
 				$$( document ).on( 'click', function( event ) {
 					var id, mode,
 						target = $$( event.target );
@@ -22,6 +53,16 @@
 			}
 		}
 
+		/**
+		 * @summary Retrieves the height of the toolbar based on the container the
+		 * editor is placed in.
+		 *
+		 * @since 3.9.0
+		 *
+		 * @param {Object} editor The tinyMCE editor.
+		 * @returns {number} If the height is between 10 and 200 return the height,
+		 * else return 30.
+		 */
 		function getToolbarHeight( editor ) {
 			var node = $$( '.mce-toolbar-grp', editor.getContainer() )[0],
 				height = node && node.clientHeight;
@@ -33,6 +74,20 @@
 			return 30;
 		}
 
+		/**
+		 * @summary Switches the editor between visual and text.
+		 *
+		 * @since 4.3.0
+		 *
+		 * @memberof switchEditors
+		 *
+		 * @param {string} id The id of the editor you want to change the editor mode for.
+		 * If no id is given, it defaults to content.
+		 * @param {string} mode The mode you want to switch to.
+		 * If an undefined mode is given, it defaults to toggle.
+		 *
+		 * @returns {void}
+		 */
 		function switchEditor( id, mode ) {
 			id = id || 'content';
 			mode = mode || 'toggle';
@@ -43,6 +98,7 @@
 				$textarea = $$( '#' + id ),
 				textarea = $textarea[0];
 
+			// Toggle the mode between visual and textual representation.
 			if ( 'toggle' === mode ) {
 				if ( editor && ! editor.isHidden() ) {
 					mode = 'html';
@@ -51,11 +107,20 @@
 				}
 			}
 
+
+			// If the mode is tmce or tinymce, show the editor.
 			if ( 'tmce' === mode || 'tinymce' === mode ) {
+
+				/*
+				 * If the editor isn't hidden we are already in tmce mode
+				 * and we don't need to switch.
+				 * Return false to stop event bubbling.
+				 */
 				if ( editor && ! editor.isHidden() ) {
 					return false;
 				}
 
+				// Close the QuickTags toolbars if they are visible.
 				if ( typeof( window.QTags ) !== 'undefined' ) {
 					window.QTags.closeAllTags( id );
 				}
@@ -65,12 +130,12 @@
 				if ( editor ) {
 					editor.show();
 
-					// No point resizing the iframe in iOS
+					// Don't resize the iframe in iOS.
 					if ( ! tinymce.Env.iOS && editorHeight ) {
 						toolbarHeight = getToolbarHeight( editor );
 						editorHeight = editorHeight - toolbarHeight + 14;
 
-						// height cannot be under 50 or over 5000
+						// Height must be between 50 and 5000.
 						if ( editorHeight > 50 && editorHeight < 5000 ) {
 							editor.theme.resizeTo( null, editorHeight );
 						}
@@ -83,12 +148,21 @@
 				$textarea.attr( 'aria-hidden', true );
 				window.setUserSetting( 'editor', 'tinymce' );
 
+			// Hide the editor if mode is html.
 			} else if ( 'html' === mode ) {
+
+				/*
+				 * If the editor is hidden we are already in html mode and
+				 * we don't need to switch.
+				 * Return false to stop event bubbling.
+				 */
 				if ( editor && editor.isHidden() ) {
 					return false;
 				}
 
 				if ( editor ) {
+
+					// Don't resize the iframe in iOS.
 					if ( ! tinymce.Env.iOS ) {
 						iframe = editor.iframeElement;
 						editorHeight = iframe ? parseInt( iframe.style.height, 10 ) : 0;
@@ -97,7 +171,7 @@
 							toolbarHeight = getToolbarHeight( editor );
 							editorHeight = editorHeight + toolbarHeight - 14;
 
-							// height cannot be under 50 or over 5000
+							// Height must be between 50 and 5000.
 							if ( editorHeight > 50 && editorHeight < 5000 ) {
 								textarea.style.height = editorHeight + 'px';
 							}
@@ -106,7 +180,7 @@
 
 					editor.hide();
 				} else {
-					// The TinyMCE instance doesn't exist, show the textarea
+					// The TinyMCE instance doesn't exist, show the textarea.
 					$textarea.css({ 'display': '', 'visibility': '' });
 				}
 
@@ -116,7 +190,22 @@
 			}
 		}
 
-		// Replace paragraphs with double line breaks
+		/**
+		 * @summary Replaces all paragraphs with double line breaks.
+		 *
+		 * Replaces all paragraphs with double line breaks. Taking into account
+		 * the elements where the <p> should be preserved.
+		 * Unifies all whitespaces.
+		 * Adds indenting with tabs to li, dt and dd elements.
+		 * Trims whitespaces from beginning and end of the html input.
+		 *
+		 * @since 4.3.0
+		 *
+		 * @memberof switchEditors
+		 *
+		 * @param {string} html The content from the editor.
+		 * @return {string} The formatted html string.
+		 */
 		function removep( html ) {
 			var blocklist = 'blockquote|ul|ol|li|dl|dt|dd|table|thead|tbody|tfoot|tr|th|td|h[1-6]|fieldset',
 				blocklist1 = blocklist + '|div|p',
@@ -129,7 +218,10 @@
 				return '';
 			}
 
-			// Preserve script and style tags.
+			/*
+			 * Protect script and style tags by replacing them with <wp-preserve>.
+			 * Push matches into the preserve array.
+			 */
 			if ( html.indexOf( '<script' ) !== -1 || html.indexOf( '<style' ) !== -1 ) {
 				html = html.replace( /<(script|style)[^>]*>[\s\S]*?<\/\1>/g, function( match ) {
 					preserve.push( match );
@@ -137,7 +229,10 @@
 				} );
 			}
 
-			// Protect pre tags.
+			/*
+			 * Protect pre tags by replacing all newlines and
+			 * <br> tags with <wp-line-break>.
+			 */
 			if ( html.indexOf( '<pre' ) !== -1 ) {
 				preserve_linebreaks = true;
 				html = html.replace( /<pre[^>]*>[\s\S]+?<\/pre>/g, function( a ) {
@@ -147,7 +242,10 @@
 				});
 			}
 
-			// keep <br> tags inside captions and remove line breaks
+			/*
+			 * Keep <br> tags inside captions and remove line breaks by replacing
+			 * them with <wp-temp-br>.
+			 */
 			if ( html.indexOf( '[caption' ) !== -1 ) {
 				preserve_br = true;
 				html = html.replace( /\[caption[\s\S]+?\[\/caption\]/g, function( a ) {
@@ -155,66 +253,96 @@
 				});
 			}
 
-			// Pretty it up for the source editor
+			// Format the text to be readable in the source editor.
 			html = html.replace( new RegExp( '\\s*</(' + blocklist1 + ')>\\s*', 'g' ), '</$1>\n' );
 			html = html.replace( new RegExp( '\\s*<((?:' + blocklist1 + ')(?: [^>]*)?)>', 'g' ), '\n<$1>' );
 
 			// Mark </p> if it has any attributes.
 			html = html.replace( /(<p [^>]+>.*?)<\/p>/g, '$1</p#>' );
 
-			// Separate <div> containing <p>
+			// If the content of a container starts with a paragraph, replace the <p> tag with 2 newlines.
 			html = html.replace( /<div( [^>]*)?>\s*<p>/gi, '<div$1>\n\n' );
 
-			// Remove <p> and <br />
+			// Remove <p> and </p> tags.
 			html = html.replace( /\s*<p>/gi, '' );
 			html = html.replace( /\s*<\/p>\s*/gi, '\n\n' );
+
+			// Remove white spaces between newlines. u00a0 is a no breaking space.
 			html = html.replace( /\n[\s\u00a0]+\n/g, '\n\n' );
+
+			// Remove <br> tags.
 			html = html.replace( /\s*<br ?\/?>\s*/gi, '\n' );
 
-			// Fix some block element newline issues
+			/*
+			 * Fix some block element newline issues.
+			 * Replace white spaces with newlines in combination with <div> tags.
+			 */
 			html = html.replace( /\s*<div/g, '\n<div' );
 			html = html.replace( /<\/div>\s*/g, '</div>\n' );
+
+			// Replace white spaces with newlines in combination with [caption] shortcodes.
 			html = html.replace( /\s*\[caption([^\[]+)\[\/caption\]\s*/gi, '\n\n[caption$1[/caption]\n\n' );
+
+			/*
+			 * Limit the newlines in combination with [caption]'s to a maximum of
+			 * two consecutive occurrences.
+			 * .
+			 */
 			html = html.replace( /caption\]\n\n+\[caption/g, 'caption]\n\n[caption' );
 
+			/*
+			 * Replace white spaces with newlines in combination with
+			 * all elements listed in blocklist2.
+			 */
 			html = html.replace( new RegExp('\\s*<((?:' + blocklist2 + ')(?: [^>]*)?)\\s*>', 'g' ), '\n<$1>' );
 			html = html.replace( new RegExp('\\s*</(' + blocklist2 + ')>\\s*', 'g' ), '</$1>\n' );
+
+			// Add indentation by adding a tab in front of <li>, <dt> and <dd> tags.
 			html = html.replace( /<((li|dt|dd)[^>]*)>/g, ' \t<$1>' );
 
+			// Replace white spaces with newlines in combination with <select> and <option> tags.
 			if ( html.indexOf( '<option' ) !== -1 ) {
 				html = html.replace( /\s*<option/g, '\n<option' );
 				html = html.replace( /\s*<\/select>/g, '\n</select>' );
 			}
 
+			// Replace white spaces with 2 newlines in combination with <hr> tags.
 			if ( html.indexOf( '<hr' ) !== -1 ) {
 				html = html.replace( /\s*<hr( [^>]*)?>\s*/g, '\n\n<hr$1>\n\n' );
 			}
 
+			// Remove newlines in <object> tags.
 			if ( html.indexOf( '<object' ) !== -1 ) {
 				html = html.replace( /<object[\s\S]+?<\/object>/g, function( a ) {
 					return a.replace( /[\r\n]+/g, '' );
 				});
 			}
 
-			// Unmark special paragraph closing tags
+			// Unmark special paragraph closing tags.
 			html = html.replace( /<\/p#>/g, '</p>\n' );
+
+
+			// Add a new line before <p> tags when there is content inside the paragraph
 			html = html.replace( /\s*(<p [^>]+>[\s\S]*?<\/p>)/g, '\n$1' );
 
-			// Trim whitespace
+			/*
+			 * Remove whitespaces at the start and end of a string.
+			 * u00a0 is a no breaking space.
+			 */
 			html = html.replace( /^\s+/, '' );
 			html = html.replace( /[\s\u00a0]+$/, '' );
 
-			// put back the line breaks in pre|script
+			// Replace <wp-line-break> tags with a newline.
 			if ( preserve_linebreaks ) {
 				html = html.replace( /<wp-line-break>/g, '\n' );
 			}
 
-			// and the <br> tags in captions
+			// Restore the <wp-temp-br> with <br> tags.
 			if ( preserve_br ) {
 				html = html.replace( /<wp-temp-br([^>]*)>/g, '<br$1>' );
 			}
 
-			// Put back preserved tags.
+			// Restore preserved tags.
 			if ( preserve.length ) {
 				html = html.replace( /<wp-preserve>/g, function() {
 					return preserve.shift();
@@ -224,32 +352,52 @@
 			return html;
 		}
 
-		// Similar to `wpautop()` in formatting.php
+		/**
+		 * @summary Adds paragraph tags to the text.
+		 *
+		 * Adds paragraph tags to the text taking into account block level elements.
+		 * Normalizes the whitespaces and newlines.
+		 *
+		 * Similar to `wpautop()` in formatting.php.
+		 *
+		 * @since 4.3.0
+		 *
+		 * @memberof switchEditors
+		 *
+		 * @param {string} text The text input.
+		 * @returns {string} The formatted text.
+		 */
 		function autop( text ) {
 			var preserve_linebreaks = false,
 				preserve_br = false,
+
+				// A list containing all block level elements.
 				blocklist = 'table|thead|tfoot|caption|col|colgroup|tbody|tr|td|th|div|dl|dd|dt|ul|ol|li|pre' +
 					'|form|map|area|blockquote|address|math|style|p|h[1-6]|hr|fieldset|legend|section' +
 					'|article|aside|hgroup|header|footer|nav|figure|figcaption|details|menu|summary';
 
-			// Normalize line breaks
+			// Normalize line breaks.
 			text = text.replace( /\r\n|\r/g, '\n' );
 
+			// If there are no newlines, return the text.
 			if ( text.indexOf( '\n' ) === -1 ) {
 				return text;
 			}
 
 			if ( text.indexOf( '<object' ) !== -1 ) {
+
+				// If there are multiple newlines in an <object>, remove them.
 				text = text.replace( /<object[\s\S]+?<\/object>/g, function( a ) {
 					return a.replace( /\n+/g, '' );
 				});
 			}
 
+			// Replace all new lines and tabs with spaces inside tags.
 			text = text.replace( /<[^<>]+>/g, function( a ) {
 				return a.replace( /[\n\t ]+/g, ' ' );
 			});
 
-			// Protect pre|script tags
+			// Protect <pre> and <script> tags by replacing them with <wp-line-break>.
 			if ( text.indexOf( '<pre' ) !== -1 || text.indexOf( '<script' ) !== -1 ) {
 				preserve_linebreaks = true;
 				text = text.replace( /<(pre|script)[^>]*>[\s\S]*?<\/\1>/g, function( a ) {
@@ -257,61 +405,138 @@
 				});
 			}
 
-			// keep <br> tags inside captions and convert line breaks
+			// Keep <br> tags inside captions.
 			if ( text.indexOf( '[caption' ) !== -1 ) {
 				preserve_br = true;
+
+				// Replace all white spaces and <br> tags with <wp-temp-br>.
 				text = text.replace( /\[caption[\s\S]+?\[\/caption\]/g, function( a ) {
-					// keep existing <br>
+
+					// Protect <br> tags by converting them to <wp-temp-br> tags.
 					a = a.replace( /<br([^>]*)>/g, '<wp-temp-br$1>' );
-					// no line breaks inside HTML tags
+
+					// Replace all new lines and tabs with spaces inside HTML tags.
 					a = a.replace( /<[^<>]+>/g, function( b ) {
+
+						// Replace newlines and tabs with a space.
 						return b.replace( /[\n\t ]+/, ' ' );
 					});
-					// convert remaining line breaks to <br>
+
+					// Convert remaining line breaks to <wp-temp-br />.
 					return a.replace( /\s*\n\s*/g, '<wp-temp-br />' );
 				});
 			}
 
+			// Append 2 newlines at the end of the text.
 			text = text + '\n\n';
+
+			/*
+			 * Replace a <br> tag followed by 1 or more spaces
+			 * and another <br> tag with 2 newlines.
+			 */
 			text = text.replace( /<br \/>\s*<br \/>/gi, '\n\n' );
+
+			/*
+			 * Replace a block level element open tag with 2 newlines
+			 * followed by the captured block level element.
+			 */
 			text = text.replace( new RegExp( '(<(?:' + blocklist + ')(?: [^>]*)?>)', 'gi' ), '\n\n$1' );
+
+			/*
+			 * Replace a block level element closing tag with the captured
+			 * block level element followed by 2 newlines.
+			 */
 			text = text.replace( new RegExp( '(</(?:' + blocklist + ')>)', 'gi' ), '$1\n\n' );
-			text = text.replace( /<hr( [^>]*)?>/gi, '<hr$1>\n\n' ); // hr is self closing block element
-			text = text.replace( /\s*<option/gi, '<option' ); // No <p> or <br> around <option>
+
+			// Add 2 newlines to a <hr> tag. <hr> is a self closing block element.
+			text = text.replace( /<hr( [^>]*)?>/gi, '<hr$1>\n\n' );
+
+			// Remove the spaces before an <option> tag.
+			text = text.replace( /\s*<option/gi, '<option' );
+
+			// Remove the spaces after an <option> closing tag.
 			text = text.replace( /<\/option>\s*/gi, '</option>' );
+
+			// Remove the spaces between two newlines.
 			text = text.replace( /\n\s*\n+/g, '\n\n' );
+
+			// Convert 2 newlines to a paragraph and a single newline.
 			text = text.replace( /([\s\S]+?)\n\n/g, '<p>$1</p>\n' );
+
+			// Remove empty paragraphs.
 			text = text.replace( /<p>\s*?<\/p>/gi, '');
+
+			// Remove spaces and <p> tags around block level elements.
 			text = text.replace( new RegExp( '<p>\\s*(</?(?:' + blocklist + ')(?: [^>]*)?>)\\s*</p>', 'gi' ), '$1' );
+
+			// Remove <p> tags around li elements.
 			text = text.replace( /<p>(<li.+?)<\/p>/gi, '$1');
+
+			// Remove spaces and <p> tags from blockquotes.
 			text = text.replace( /<p>\s*<blockquote([^>]*)>/gi, '<blockquote$1><p>');
+
+			// Place the <blockquote> outside of the paragraph.
 			text = text.replace( /<\/blockquote>\s*<\/p>/gi, '</p></blockquote>');
+
+			// Remove spaces at the start and <p> tags from block level elements.
 			text = text.replace( new RegExp( '<p>\\s*(</?(?:' + blocklist + ')(?: [^>]*)?>)', 'gi' ), '$1' );
+
+			// Remove spaces at the end and <p> tags from block level elements.
 			text = text.replace( new RegExp( '(</?(?:' + blocklist + ')(?: [^>]*)?>)\\s*</p>', 'gi' ), '$1' );
 
-			// Remove redundant spaces and line breaks after existing <br /> tags
+			// Remove spaces and newlines after a <br> tag.
 			text = text.replace( /(<br[^>]*>)\s*\n/gi, '$1' );
 
-			// Create <br /> from the remaining line breaks
+			// Replace spaces followed by a newline with a <br> tag followed by a new line.
 			text = text.replace( /\s*\n/g, '<br />\n');
 
+			// Remove <br> tag that follows a block element directly, ignoring spaces.
 			text = text.replace( new RegExp( '(</?(?:' + blocklist + ')[^>]*>)\\s*<br />', 'gi' ), '$1' );
+
+			/*
+			 * Remove a br tag preceding white spaces followed by a
+			 * <p>, <li>, <div>, <dl>, <dd>, <dt>, <th>, <pre>, <td>, <ul>, or <ol> tag.
+			 */
 			text = text.replace( /<br \/>(\s*<\/?(?:p|li|div|dl|dd|dt|th|pre|td|ul|ol)>)/gi, '$1' );
+
+			// Remove white spaces, <p> and <br> tags in captions.
 			text = text.replace( /(?:<p>|<br ?\/?>)*\s*\[caption([^\[]+)\[\/caption\]\s*(?:<\/p>|<br ?\/?>)*/gi, '[caption$1[/caption]' );
 
+			/**
+			 * @summary Makes sure there is a paragraph open tag for a close tag.
+			 *
+			 * @since 2.9.0
+			 *
+			 * Makes sure there is a paragraph open tag when there is a paragraph close tag
+			 * in a div, th, td, form, fieldset or dd element.
+			 * @param {string} a The complete match.
+			 * @param {string} b The first capture group.
+			 * @param {string} c The second capture group.
+			 * @returns {string} The string in paragraph tags.
+			 */
 			text = text.replace( /(<(?:div|th|td|form|fieldset|dd)[^>]*>)(.*?)<\/p>/g, function( a, b, c ) {
+
+				/*
+				 * Check if the matched group has a p open tag in it. If so, we don't need to
+				 * enclose it with a paragraph.
+				 */
 				if ( c.match( /<p( [^>]*)?>/ ) ) {
 					return a;
 				}
 
+				/*
+				 * If there is no p open tag in the matched string,
+				 * add it and return the string including p tags.
+				 */
 				return b + '<p>' + c + '</p>';
 			});
 
-			// put back the line breaks in pre|script
+			// Restore the line breaks in <pre> and <script> tags.
 			if ( preserve_linebreaks ) {
 				text = text.replace( /<wp-line-break>/g, '\n' );
 			}
 
+			// Restore the <br> tags in captions.
 			if ( preserve_br ) {
 				text = text.replace( /<wp-temp-br([^>]*)>/g, '<br$1>' );
 			}
@@ -319,7 +544,21 @@
 			return text;
 		}
 
-		// Add old events
+		/**
+		 * @summary Modifies the data when a switch is made from HTML to text.
+		 *
+		 * Modifies the data when a switch is made.
+		 * Remove the <p> tags from text.
+		 * Returns the modified text.
+		 * Adds a trigger on beforePreWpautop and afterPreWpautop.
+		 *
+		 * @since 2.5.0
+		 *
+		 * @memberof switchEditors
+		 *
+		 * @param {String} html The content from the visual editor.
+		 * @returns {String} the modified text.
+		 */
 		function pre_wpautop( html ) {
 			var obj = { o: exports, data: html, unfiltered: html };
 
@@ -336,6 +575,19 @@
 			return obj.data;
 		}
 
+		/**
+		 * @summary Modifies the data when a switch is made from text to HTML.
+		 *
+		 * Modifies the data when a switch is made. Runs autop to add p tags from text.
+		 * Returns the modified text. Adds a trigger on beforeWpautop and afterWpautop.
+		 *
+		 * @since 2.5.0
+		 *
+		 * @memberof switchEditors
+		 *
+		 * @param {String} text The content from the text editor.
+		 * @returns {String} the modified text.
+		 */
 		function wpautop( text ) {
 			var obj = { o: exports, data: text, unfiltered: text };
 
@@ -352,12 +604,18 @@
 			return obj.data;
 		}
 
+		// Bind the init function to be run when the document is loaded.
 		if ( $ ) {
 			$( document ).ready( init );
 		} else if ( document.addEventListener ) {
+
+			// Use the addEventListener to bind the init event on document load.
 			document.addEventListener( 'DOMContentLoaded', init, false );
 			window.addEventListener( 'load', init, false );
+
 		} else if ( window.attachEvent ) {
+
+			// Use the addEvent to bind the init event on document load.
 			window.attachEvent( 'onload', init );
 			document.attachEvent( 'onreadystatechange', function() {
 				if ( 'complete' === document.readyState ) {
@@ -366,6 +624,10 @@
 			} );
 		}
 
+		/*
+		 * Make sure the window.wp object exists so autop and removep
+		 * can be bound to it.
+		 */
 		window.wp = window.wp || {};
 		window.wp.editor = window.wp.editor || {};
 		window.wp.editor.autop = wpautop;
@@ -382,5 +644,9 @@
 		return exports;
 	}
 
+	/**
+	 * @namespace {SwitchEditors} switchEditors
+	 * Expose the switch editors to be used globally.
+	 */
 	window.switchEditors = new SwitchEditors();
 }( window.jQuery ));