学步园

创建一个XmlHttpRequest对象的函数：
     function CreateXMLHttpRequest() {
         var request = false;
         if (window.XMLHttpRequest) {
             request = new XMLHttpRequest();
             if (request.overrideMimeType) {
                 request.overrideMimeType('text/xml');
             }
         } else if (window.ActiveXObject) {
             try {
                 request = new ActiveXObject("Msxml2.XMLHTTP");
             } catch (e) {
                 try {
                     request = new ActiveXObject("Microsoft.XMLHTTP");
                 } catch (e) {return false;}
             }
         }
         if (!request) {
             alert('Create XMLHTTP Object false.');
             return false;
         }
         return request;
     }