XMLHTTPRequest Polyfill

request.js

function makeRequest(url,callback,context) {
  var httpRequest = null;
  if (window.XMLHttpRequest) { // Mozilla, Safari, ...
    httpRequest = new XMLHttpRequest();
  } else if (window.ActiveXObject) { // IE
    try {
      httpRequest = new ActiveXObject("Msxml2.XMLHTTP");
    }
    catch (e) {
      try {
        httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
      }
      catch (e) {
        console.log('error');
      }
    }
  }

  if (!httpRequest) {
    alert('Giving up :( Cannot create an XMLHTTP instance');
    return false;
  }

  function serveContent(){
    if (httpRequest.readyState === 4) {
      if (httpRequest.status === 200) {
        callback.call(context,JSON.parse(httpRequest.responseText));
      } else {
        console.log('There was a problem with the request.');
      }
    }
  }

  httpRequest.onreadystatechange = serveContent;
  httpRequest.open('GET', url);
  httpRequest.send();
}