XMLHttpRequest in IE6

xhr-ie6.js

// An alternative implementation to the createXHR function for creating
// an XHR object in all modern browsers as well as emulating IE5 and IE6.

if (window.XMLHttpRequest === undefined) {
  window.XMLHttpRequest = function() {
    try {
      // Use the latest version of the ActiveX object if available
      return new ActiveXObject("Msxml2.XMLHTTP.6.0");
    }
    catch(e1) {
      try {
        // Otherwise fall back to older version
        return new ActiveXObject("Msxml2.XMLHTTP.3.0");
      }
      catch(e2) {
        // But if the older version is not available, throw an error
        throw new Error("XMLHttpRequest is not supported");
      }
    }
  };
}