Referencing a Script’s Own Tag

There are times when the contents of an external script may want to reference its own SCRIPT tag.  There are times that developers may want to detect attributes of the script tag which act as options for the script; this is a practice that's been done by the Dojo Toolkit for years.  Lea Verou's Prism syntax highlighter also uses this practice:

<!-- Traditional Dojo config -->
<script src="//ajax.googleapis.com/ajax/libs/dojo/1.8.3/dojo/dojo.js"
               data-dojo-config="async: true"></script>

<!-- Sample Prism config -->
<script src="prism.js" data-default-language="markup" data-manual></script>

So how are these projects getting the correct SCRIPT tag with which to look for attributes?  Assuming a top-down (not async) load of scripts, the following will get a script its own tag:

/* From in side the script.... */

// Reliably grab my script tag
var script = document.getElementsByTagName("script");
script = script[script.length - 1];

// Check for an attribute/config
if(script.hasAttribute('data-something')) {
	// Do something!
}

Collect the SCRIPT elements up to that point and reference the last one -- that's all you need to do.  Of course we're living in a mostly async world right now, so to accommodate for those cases, you may need to stick an ID on the SCRIPT element, take a chance matching the SCRIPT by path (a really bad idea), or use a different type of configuration system.

document.currentScript

A document.currentScript property also exists, and this standard property provides the ultimate reliable method of detecting the currently executing script:

var script = document.currentScript;

Pairing this method with the older solution, the best complete code solution could be this:

var script = document.currentScript || (function() {
    var scripts = document.getElementsByTagName("script");
    return scripts[scripts.length - 1];
})();