                        課程
                    
                        /前端開發(fā)
                        
                            /JavaScript
                        
                        /Ajax全接觸

ajax的open()

<%@ page language="java" contentType="text/html; charset=UTF-8"
??? pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
<script type="text/javascript">
?? ?window.onload=function(){
?? ??? ?//1.獲取 a 節(jié)點(diǎn)，并為其添加 onclick 響應(yīng)函數(shù)
?? ??? ?document.getElementsByTagName("a")[0].onclick=function(){
?? ??? ??? ?//3.創(chuàng)建一個(gè) XMLHttpRequest 對象
?? ??? ??? ?var request=new XMLHttpRequest();
?? ??? ??? ?//4.準(zhǔn)備發(fā)送請求的 method 和 url
?? ??? ??? ?var url=this.href;
?? ??? ??? ?var method="GET";
?? ??? ??? ?alert(3);
?? ??? ??? ?//5.調(diào)用 XMLHttpRequset 對象的 open() 方法? (準(zhǔn)備請求)
?? ??? ??? ?request.open(method,url);
?? ??? ??? ?
?? ??? ??? ?alert(4);
?? ??? ??? ?//6.調(diào)用 XMLHttpRquest 對象的 send() 方法?? ? (發(fā)送請求)
?? ??? ??? ?request.send();
?? ??? ??? ?//7.為 XMLHttpRquest 對象添加onreadystatechange 響應(yīng)函數(shù)
?? ??? ??? ?request.onreadystatechange=function(){
?? ??? ??? ?//8.判斷響應(yīng)是否完成：XMLHttpRequest 對象的 readystate屬性值為? 4? 的時(shí)候
?? ??? ??? ??? ?if(request.readystate==4){
?? ??? ??? ??? ?//9.再判斷是否可用：XMLHttpRequest 對象的 status 屬性為值 200
?? ??? ??? ??? ??? ?if(request.status==200 || request.status==304){
?? ??? ??? ??? ??? ??? ??? ?//10.打印響應(yīng)的結(jié)果： responseText
?? ??? ??? ??? ??? ??? ?alert(request.responesText);
?? ??? ??? ??? ??? ?}?? ??? ??? ??? ??? ?
?? ??? ??? ??? ?}
?? ??? ??? ?}
?? ??? ??? ?//2.取消a節(jié)點(diǎn)的默認(rèn)行為
?? ??? ??? ?return false;
?? ??? ?}
?? ?}
</script>
</head>
<body>
?? ?<a href="helloAjax.txt">HelloAjax</a>
</body>
</html>