php: str_replace or preg_match?

How about a single regex using preg_replace? It will also work for href and src attributes. Be sure to check the demo to see it in action!

This converts all of the above test cases correctly:

$result = preg_replace( '/(src|href)="(?:\.\.\/|\/)?([^"]+)"/i', '$1="' . $url . '/$2"', $test);

Demo

That's not really a good comparison. Those two functions serve separate purposes. I would personally use three, in this order:

If it becomes more than 3, use

$pathes=array(
  'src="/jsfile.js' => 'src="http://mysite.com/jsfile.js',
  'src="../jsfile.js' => 'src="http://mysite.com/jsfile.js',
  'src="js/jsfile.js' => 'src="http://mysite.com/js/jsfile.js'
);


$newhtml=str_replace(array_keys($pathes),$pathes,$oldhtml);

<?php
$html = file_get_contents('index.html');
$html = preg_replace_callback('#"(\S+).js"#', "replace_url", $html);
function replace_url($url) {
return '"http://'.$_SERVER['HTTP_HOST'].chr(47).trim($url[1], '/,.').'.js"';
}
echo $html;

Use preg_replace_callback