JSONP XMLHttp Requests

// define a 'success' callback to handle the results of the request
success = function () {
   // this is called on success
}

// add the callback function 'success' as the query parameter 'callback'
var url = "http://www.api.com/endpoint?callback=success";


// create a new SCRIPT tag, assign the url to the 'src' attribute and append to the HEAD tag
var s = document.createElement("script");
s.src = url;
document.getElementsByTagName("head")[0].appendChild(s);

// couldn't be easier