原生JS操作AJAX

1，get方式的AJAX

 function sendAjaxReq()
 {
     //1,创建ajax引擎 XMLHttpRequest对象
     var req = new XMLHttpRequest() || new ActiveXObject("Msxm12.XMLHTTP");
     //2,打开一个请求，此时未发送请求，定义好发送请求的方式以及是否需要携带数据 是否同步异步
     req.open("get", "testAjax?phone=iphone&apple=pen");
     //3,准备好处理服务器返回的数据
     req.onreadystatechange = function()
     {
         if(req.readyState == 4)
         {
             //返回json数据的解析格式
             var str = req.responseText;
             eval("var obj=" + str);
             alert(obj.name);
             //返回xml的解析格式
             var data = req.reponseXML.getElementsByTagName("bigName")[0].first(child.data);
         }
     }
     //4,发送请求,如果是在火狐下，使用get方式发送ajax请求，send的时候括号写上null
     req.send(null);
 }

2，post方式AJAX

 //使用post传参，需要携带一个请求头模拟表单提交
 function sendAjax()
 {
     var request = new XMLHttpRequest() || new ActiveXObject("Msxm12.XMLHTTP");
     request.open("post", "testAjax?phone=1", true)
     request.onreadystatechange = function()
     {
         if(request.readyState == 4)
         {
             if(request.status == 200)
             {
                 var str = request.responseText;
                 alert(str);
             }
             else if(request.status == 404)
             {
                 alert("找不到资源");
             }
         }
     }
     request.setRequestHeader("content-type", "application/x-www-form-urlencoded")
     request.send("phone=");
 }

3，封装了get和post的AJAX

 function sendAjaxReq(method,url,param,fun200,fun404,fun500)
  {
      var req;
       if(window.XMLHttpRequest)
       {
           req = new XMLHttpRequest();
       }
           else if(window.ActiveXObject)
       {
          req = new ActiveXObject("Msxml2.XMLHTTP");
       }
       req.open(method,url);
       req.onreadystatechange = function()
       {
           if(req.readyState == 4)
           {
               if(req.status == 200)
               {
                   if(fun200)
                   {
                      fun200(req.responseText);
                   }
               }
               else if(req.status == 404)
               {
                   if(fun404)
                   {
                       fun404();
                   }
               }
               else if(req.status == 500)
               {
                   if(fun500)
                   {
                       fun500();
                   }
               }
           }
       }
       if(method.toUpperCase() == "GET")
       {
           req.send(null);
       }
       else if(method.toUpperCase() == "POST")
       {
           req.setRequestHeader("context-type", "application/x-www-form-urlencoded");
           req.send(param);
       }
   }

 function testAjax()
 {
     sendAjaxReq("get","ajaxServlet?uname=1&password=2",null,function(data)
     {
         eval("var obj="+data);
         alert(obj.data);
     });
 }