diff --git a/src/js/_enqueues/lib/auth-check.js b/src/js/_enqueues/lib/auth-check.js
index a501d01e7f..158b6e1750 100644
--- a/src/js/_enqueues/lib/auth-check.js
+++ b/src/js/_enqueues/lib/auth-check.js
@@ -8,6 +8,12 @@
 (function($){
 	var wrap, next;
 
+	/**
+	 * Shows the authentication form popup.
+	 *
+	 * @since 3.6.0
+	 * @private
+	 */
 	function show() {
 		var parent = $('#wp-auth-check'),
 			form = $('#wp-auth-check-form'),
@@ -15,7 +21,7 @@
 			frame, loaded = false;
 
 		if ( form.length ) {
-			// Add unload confirmation to counter (frame-busting) JS redirects
+			// Add unload confirmation to counter (frame-busting) JS redirects.
 			$(window).on( 'beforeunload.wp-auth-check', function(e) {
 				e.originalEvent.returnValue = window.authcheckL10n.beforeunload;
 			});
@@ -45,7 +51,8 @@
 					else
 						parent.css( 'max-height', height + 40 + 'px' );
 				} else if ( ! body || ! body.length ) {
-					// Catch "silent" iframe origin exceptions in WebKit after another page is loaded in the iframe
+					// Catch "silent" iframe origin exceptions in WebKit after another page is
+					// loaded in the iframe.
 					wrap.addClass('fallback');
 					parent.css( 'max-height', '' );
 					form.remove();
@@ -61,7 +68,8 @@
 
 		if ( frame ) {
 			frame.focus();
-			// WebKit doesn't throw an error if the iframe fails to load because of "X-Frame-Options: DENY" header.
+			// WebKit doesn't throw an error if the iframe fails to load because of
+			// "X-Frame-Options: DENY" header.
 			// Wait for 10 sec. and switch to the fallback text.
 			setTimeout( function() {
 				if ( ! loaded ) {
@@ -75,10 +83,17 @@
 		}
 	}
 
+	/**
+	 * Hides the authentication form popup.
+	 *
+	 * @since 3.6.0
+	 * @private
+	 */
 	function hide() {
 		$(window).off( 'beforeunload.wp-auth-check' );
 
-		// When on the Edit Post screen, speed up heartbeat after the user logs in to quickly refresh nonces
+		// When on the Edit Post screen, speed up heartbeat after the user logs in to
+		// quickly refresh nonces.
 		if ( typeof adminpage !== 'undefined' && ( adminpage === 'post-php' || adminpage === 'post-new-php' ) &&
 			typeof wp !== 'undefined' && wp.heartbeat ) {
 
@@ -93,11 +108,32 @@
 		});
 	}
 
+	/**
+	 * Schedules when the next time the authentication check will be done.
+	 *
+	 * @since 3.6.0
+	 * @private
+	 */
 	function schedule() {
-		var interval = parseInt( window.authcheckL10n.interval, 10 ) || 180; // in seconds, default 3 min.
+		// In seconds, default 3 min.
+		var interval = parseInt( window.authcheckL10n.interval, 10 ) || 180;
 		next = ( new Date() ).getTime() + ( interval * 1000 );
 	}
 
+	/**
+	 * Binds to the Heartbeat Tick event.
+	 *
+	 * - Shows the authentication form popup if user is not logged in.
+	 * - Hides the authentication form popup if it is already visible and user is
+	 *   logged in.
+	 *
+	 * @ignore
+	 *
+	 * @since 3.6.0
+	 *
+	 * @param {Object} e The heartbeat-tick event that has been triggered.
+	 * @param {Object} data Response data.
+	 */
 	$( document ).on( 'heartbeat-tick.wp-auth-check', function( e, data ) {
 		if ( 'wp-auth-check' in data ) {
 			schedule();
@@ -107,12 +143,32 @@
 				hide();
 			}
 		}
+
+	/**
+	 * Binds to the Heartbeat Send event.
+	 *
+	 * @ignore
+	 *
+	 * @since 3.6.0
+	 *
+	 * @param {Object} e The heartbeat-send event that has been triggered.
+	 * @param {Object} data Response data.
+	 */
 	}).on( 'heartbeat-send.wp-auth-check', function( e, data ) {
 		if ( ( new Date() ).getTime() > next ) {
 			data['wp-auth-check'] = true;
 		}
+
 	}).ready( function() {
 		schedule();
+
+		/**
+		 * Hides the authentication form popup when the close icon is clicked.
+		 *
+		 * @ignore
+		 *
+		 * @since 3.6.0
+		 */
 		wrap = $('#wp-auth-check-wrap');
 		wrap.find('.wp-auth-check-close').on( 'click', function() {
 			hide();