General: Optimize wp.sanitize.stripTags() to improve memory usage.

This updates the logic to use iteration instead of recursive calls, resulting in reduced memory usage and avoiding a possible stack overflow for large HTML documents.

The JS code is also tidied up with improved JSDoc and utilizing `let` instead of `var`.

Props jrchamp, sabernhardt, SirLouen, rollybueno, mukesh27, flixos90, westonruter.
Fixes #48054.


git-svn-id: https://develop.svn.wordpress.org/trunk@60907 602fd350-edb4-49c9-b593-d223f7449a82

Author: westonruter

src/js/_enqueues/wp/sanitize.js

@@ -2,6 +2,8 @@
  * @output wp-includes/js/wp-sanitize.js
  */
 
+/* eslint-env es6 */
+
 ( function () {
 
 	window.wp = window.wp || {};
@@ -16,24 +18,24 @@
 		/**
 		 * Strip HTML tags.
 		 *
-		 * @param {string} text Text to strip the HTML tags from.
+		 * @param {string} text - Text to strip the HTML tags from.
 		 *
-		 * @return  Stripped text.
+		 * @return {string} Stripped text.
 		 */
 		stripTags: function( text ) {
-			text = text || '';
+			let _text = text || '';
+
+			// Do the search-replace until there is nothing to be replaced.
+			do {
+				// Keep pre-replace text for comparison.
+				text = _text;
 
-			// Do the replacement.
-			var _text = text
+				// Do the replacement.
+				_text = text
 					.replace( /<!--[\s\S]*?(-->|$)/g, '' )
 					.replace( /<(script|style)[^>]*>[\s\S]*?(<\/\1>|$)/ig, '' )
 					.replace( /<\/?[a-z][\s\S]*?(>|$)/ig, '' );
-
-			// If the initial text is not equal to the modified text,
-			// do the search-replace again, until there is nothing to be replaced.
-			if ( _text !== text ) {
-				return wp.sanitize.stripTags( _text );
-			}
+			} while ( _text !== text );
 
 			// Return the text with stripped tags.
 			return _text;
@@ -42,12 +44,12 @@
 		/**
 		 * Strip HTML tags and convert HTML entities.
 		 *
-		 * @param {string} text Text to strip tags and convert HTML entities.
+		 * @param {string} text - Text to strip tags and convert HTML entities.
 		 *
-		 * @return Sanitized text. False on failure.
+		 * @return {string} Sanitized text.
 		 */
 		stripTagsAndEncodeText: function( text ) {
-			var _text = wp.sanitize.stripTags( text ),
+			let _text = wp.sanitize.stripTags( text ),
 				textarea = document.createElement( 'textarea' );
 
 			try {