Pure Javascript function for JSONP requests

function execJSONP(url, cb) { //url (without "callback=" parameter!) and callback function
	var script = document.createElement('script');
	script.async = true;
	var callb = 'exec'+Math.floor((Math.random()*65535)+1);
	window[callb] = function(data) {
		var scr = document.getElementById(callb);
		scr.parentNode.removeChild(scr);
		cb(data);
		window[callb] = null;
		delete window[callb];
	}
	var sepchar = (url.indexOf('?') > -1)?'&':'?';
	script.src = url+sepchar+'callback='+callb;
	script.id = callb;
	document.getElementsByTagName('head')[0].appendChild(script);
}