JavavScript : Load Js with call back

laodJs.js

//load external js 
function loadJs(src, callback) {
	s = document.createElement("script");
	s.src = "src";
	if (s.addEventListener) {
		s.addEventListener("load", callback, false);
	} else if (s.readyState) {
		s.onreadystatechange = callback;
	}
	document.body.appendChild(s);
}