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;
}