noteval.js

(function(d){
 
	window.noteval = function(/* String */code){
		// summary: Execute some javascript.
 
		if(!code) return;
 
		var	e = d.createElement("script"),
			// jump through the cross-browser hoops:
			how = "text" in e ? "text" :
				"textContent" in e ? "textContent" :
				"innerHTML" in e ? "innerHTML" :
				"appendChild"
		;
 
		if(how == "appendChild"){
			e[how](d.createTextNode(code));
		}else{
			e[how] = code;
		}
 
		return d.getElementsByTagName("head")[0].appendChild(e);
 
	};
 
})(document);
 

Why not: d.head.appendChild(e) ?

you'd have to do var head = d.head || d.getElementsByTagName("head")[0]; for x-browser anyway.

also this does little more than:

eval("(" + code + ")");

Nevermind, I answered my own question. Because document.head is not available everywhere. I use document.body.appendChild() and always found it distasteful. This is nice.

.. and is from http://higginsforpresident.net/2009/05/degrading-script-tags/

Regarding: "also this does little more than: eval("(" + code + ")");"

Thank you. Learned.