【XMLHttpRequest】获取XMLHttpRequest

// 获取http请求 function getXMLHttpRequest() {    req = false;    //本地XMLHttpRequest对象    if (window.XMLHttpRequest) {      try {       req = new XMLHttpRequest();     } catch (e) {       req = false;      }     //IE/Windows ActiveX版本    } else if (window.ActiveXObject) {      try {       req = new ActiveXObject("Msxml2.XMLHTTP");      } catch (e) {       try {         req = new ActiveXObject("Microsoft.XMLHTTP");       } catch (e) {         req = false;        }     }   }   return req; }