浏览器兼容获取XmlHttpRequest对象

functiongetXMLHttpRequest(){  if(window.XMLHttpRequest){  return new XMLHttpRequest();  }else{  var names=["msxml","msxml2","msxml3","Microsoft"];  for(vari=0;i<names.length;i++){    try{    var name=names[i]+".XMLHTTP";    return new ActiveXObject(name);    }catch(e){throw 'get request error';   }  } } return null;}