Examples of the use of XMLHttpRequest to communicate with the server contains the following three key components:
-onreadystatechange time time event handler (with server triggers, each readystate property change event will trigger readystatechange)
-open method
-send method
There are five values readystate property 01234
<%-- Created by IntelliJ IDEA. --%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>这是一个ajax的demo</title>
<script type="text/javascript">
window.onload = function () {
document.getElementsByTagName("a")[0].onclick = function () {
//1.创建XMLHttpRquest对象
var request = new XMLHttpRequest();
// 2.调用XMLHttpRequest对象的open（）方法
request.open("GET", "hello.txt");
request.send (the send method 3. Call object//null );
// add object onreadystatechange response function
request.onreadystatechange = function () {
// 4. Analyzing the response is available, then do operation response of
IF (request.readyState ==. 4 ) {
IF (== request.status == 304 || request.status 200 is ) {
// pop up in response to the text content
Alert (request.responseText);
}
}
}
return to false ;
}
}
</ Script>
</ head>
<body>
<a the href = " hello.txt "> click me </a>
</ body>
</ HTML>