Ajax Lesson 4

 1.读取响应首部
    主要Code
   

function doHeadRequest(request,url,handle)
{
 alert("start head");
 requestType=request;
 createHttpRequest();
 xmlhttp.onreadystatechange=handle;
 xmlhttp.open("HEAD",url,true);
 xmlhttp.send(null);
 
}
function defaultHeadStateHandleFunction()
{
 if(xmlhttp.readystate==4)
 {
  if(requestType=="allResponseHeaders")
  {
   getAllResponseHeader();
  }else if(requestType=="lastModified")
  {
   getLastModified();
  }else if(requestType=="isResourceAvailable")
  {
   getIsResourceAvailable();
  }
  
 } 
}

function defaultHandleFunction()
{
 if(xmlhttp.readystate==4)
 if(xmlhttp.status ==200)
 {
   doResponsed(); //Need Define yourselef.
 } 
}

function getAllResponseHeader(){
 alert(xmlhttp.getAllResponseHeaders()); 
}

function getLastModified(){
 alert("Last Modified:"+xmlhttp.getResponseHeader("Last-Modified")); 
}
function getIsResourceAvailable()
{
 if(xmlhttp.status==200)
 {
  alert("Successful response");
 }else
  if(xmlhttp.status==404)
 {
  alert("Resource is Unavailable");
 }else  
 {
  alert("UnExpected Response status:"+xmlhttp.status);
 }
}

Read.html 内容

http://www.w3.org/TR/html4/loose.dtd">

 

Reading Response Headers

  Read All Response headers
 

  Read Last Modify
 

  Read Available Resource
 

   Read Available Resource
 

注: 页面调用使用javascript:functionName ,javaScript 区分大小写.所以写的时候一定要注意.否则会出现对象无效错误.

 

2.动态刷新页面.

Dynai..html

http://www.w3.org/TR/html4/loose.dtd">

Ajax Dynamic Update Example

This page will automaticlly update itself:

 Page Will Refresh in 5 Seconds..

 
  
 

 

注.1.主要代码.SetTimeOut(function,timegap)可以固定timegap时间调用function执行.

2.需要服务器端响应.