How to encode a URL as javascript string in PHP-generated HTML?

Question

Given this PHP code:

\'\"

What if there is a \' in $url?

Answer 1

json_encode will work. You just have to use it the right way:

<a onclick="javascript:window.location.href=<?php echo htmlspecialchars(json_encode($url)); ?>">

This will work since json_encode already returns an JavaScript expression with quotes. And htmlspecialchars is needed to escape possible HTML meta characters.