typical (bad) ajax worker

script.js

//your main script
function paralellAjax(url,callback){
    var ajaxWorker = new Worker('worker.js');
    ajaxWorker.onmessage = function(e){
        callback(null,e.data);
        ajaxWorker.close();
    }
    ajaxWorker.onerror = function(e){
        callback(e);
        ajaxWorker.close();
    }
    ajaxWorker.postMessage(url);
}

worker.js

//your worker
var quickAjax = function(url,callback){
    var ajax = new XMLHttpRequest();
	ajax.onreadystatechange = function(resp){
    	if(ajax.readyState === 4 && ajax.status === 200) {
			calback(JSON.stringify(ajax.response));
		}
	}
	ajax.open('GET',url,true);
	ajax.send();
}
self.onmessage = function(e){
    quickAjax(e.data,function(resp){
        self.postMessage(resp);
    });
}