Here’s a nifty little trick that allows you to write “contextual” JavaScript. It’s incredibly obtrusive and probably shouldn’t be used at all but it’s still a pretty cool idea:

<div id="some-div">
    <script type=":contextual">
        alert(this.id); // "some-div" is alerted
    </script>
</div>

Instead of the this keyword referencing the global object (window) we can make it reference the parentNode of the script element. Here’s the code that makes it work:

(function(){
 
    var scripts = document.getElementsByTagName('script'),
        script, i = 0;
 
    while ( (script = scripts[i++]) ) {
        if ( /:contextual$/.test(script.type) ) {
            (new Function(script.innerHTML)).call(script.parentNode);
        }
    }
 
})();

Take it or leave it! – I’m indifferent either way – yes, it’s obtrusive but you’ve got to admit, contextual JavaScript looks pretty neat!

Read more »