如何查看JavaScript / PHP中是否有2条代码等效？

window.lastSavedContents = \"<?php echo htmlentities( $contents ); ?>\";

htmlentities

htmlspecialchars

<

>

&

\"

var decoded = encoded.replace(/&/g, \'&\')
                     .replace(/&lt;/g, \'<\')
                     .replace(/&quot;/g, \'\"\')
                     .replace(/&gt;/g, \'>\');

htmlentities

div

var div = document.createElement(\'div\');
div.innerHTML = encoded;
var decoded = div.firstChild.nodeValue;