JavaScript XHR

jsxhr.js

function xhr(method, uri, body, handler) {
  var req = (window.XMLHttpRequest) ? new XMLHttpRequest() : new ActiveXObject('Microsoft.XMLHTTP');
  req.onreadystatechange = function ()
  {
      if (req.readyState == 4 && handler)
      {
          eval('var o=' + req.responseText);
          handler(o);
      }
  }
  req.open(method, uri, true);
  req.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
  req.send(body);
}

xhr('POST', 'url', 'querystring', function(responseText) {
  // do something with the response
});