helloajax.js

实现Ajax的经典实例

var xmlHttpRequestHandler = new Object();
xmlHttpRequestHandler.createXmlHttpRequest = function(){
   
   var XmlHttpRequestObject;
   if (typeof XMLHttpRequest != "undefined"){
      XmlHttpRequestObject = new XMLHttpRequest();
    }
   else if (window.ActiveXObject){
        // look up the highest possible MSXML version
        var tryPossibleVersions = ["MSXML2.XMLHttp.5.0",
                                   "MSXML2.XMLHttp.4.0",
                                   "MSXML2.XMLHttp.3.0",
                                   "MSXML2.XMLHttp",
                                   "Microsoft.XMLHttp"];
      
        for (i=0; i< tryPossibleVersions.length; i++){
          try{
            XmlHttpRequestObject = new ActiveXObject(tryPossibleVersions[i]);
            break;
          }
          catch (xmlHttpRequestObjectError){
            //ignore
          }
        }
    }
    return XmlHttpRequestObject;
  }