nonobtrusive

JSONP.fetch( 'someUrl.php', {param1:'123', param2:'456'}, function(data){
        //do something with data, which is the JSON object you output from someUrl.php
        //into the callback javascript method specified by the "callback" value in the querystring
});

$myData = fetchSomeData();
 
echo $_GET['callback'];
echo "(";
echo json_encode($myData);
echo ")";

//Lightweight JSONP fetcher - www.nonobtrusive.com
var JSONP = (function(){
	var counter = 0, head, query, key, window = this;
	function load(url) {
		var script = document.createElement('script'),
			done = false;
		script.src = url;
		script.async = true;
 
		script.onload = script.onreadystatechange = function() {
			if ( !done && (!this.readyState || this.readyState === "loaded" || this.readyState === "complete") ) {
				done = true;
				script.onload = script.onreadystatechange = null;
				if ( script && script.parentNode ) {
					script.parentNode.removeChild( script );
				}
			}
		};
		if ( !head ) {
			head = document.getElementsByTagName('head')[0];
		}
		head.appendChild( script );
	}
	function jsonp(url, params, callback) {
		query = "?";
		params = params || {};
		for ( key in params ) {
			if ( params.hasOwnProperty(key) ) {
				query += key + "=" + params[key] + "&";
			}
		}
		var jsonp = "json" + (++counter);
		window[ jsonp ] = function(data){
			callback(data);
			window[ jsonp ] = null;
			try {
				delete window[ jsonp ];
			} catch (e) {}
		};
 
		load(url + query + "callback=" + jsonp);
		return jsonp;
	}
	return {
		get:jsonp
	};
}());

//Lightweight JSONP fetcher - www.nonobtrusive.com
var JSONP=(function(){var a=0,c,f,b,d=this;function e(j){var i=document.createElement("script"),h=false;i.src=j;i.async=true;i.onload=i.onreadystatechange=function(){if(!h&&(!this.readyState||this.readyState==="loaded"||this.readyState==="complete")){h=true;i.onload=i.onreadystatechange=null;if(i&&i.parentNode){i.parentNode.removeChild(i)}}};if(!c){c=document.getElementsByTagName("head")[0]}c.appendChild(i)}function g(h,j,k){f="?";j=j||{};for(b in j){if(j.hasOwnProperty(b)){f+=b+"="+j[b]+"&"}}var i="json"+(++a);d[i]=function(l){k(l);d[i]=null;try{delete d[i]}catch(m){}};e(h+f+"callback="+i);return i}return{get:g}}());