this is a simple example of php file, that place url from php code into html/javascript
in this case php code is embedded into html code using php tag <?php ... ?>
<HEAD>
<SCRIPT LANGUAGE="JavaScript">
function fullScreen(theURL) {
window.open(theURL, '', 'channelmode=yes');
}
</script>
</HEAD>
<BODY>
<a href="javascript
:void(0);" onClick="fullScreen('<?php
// this is php code
$url = "http://example.com";
echo $url;
?>');">Open Full Screen Window</a>
</body>