1 <!DOCTYPE html>
2 <html lang="en">
3 <head>
4 <meta charset="UTF-8">
5 <meta http-equiv="X-UA-Compatible" content="IE=edge">
6 <meta name="viewport" content="width=device-width, initial-scale=1.0">
7 <title>Document</title>
8 </head>
9 <body>
10 <script>
11 window.onload=function(){
12 var xhr1=null,xhr2=null, xhr3=null;
13 setTimeout(function(){
14 //实例化请求对象
15 xhr1=new XMLHttpRequest();
16 //创建请求
17 xhr1.open('get','https://cdn.bootcdn.net/ajax/libs/jquery/3.5.1/jquery.js',true)
18 //向后台发送请求
19 xhr1.send()
20
21 xhr2=new XMLHttpRequest();
22 xhr2.open('get','https://cdn.bootcdn.net/ajax/libs/vue/3.0.2/vue.cjs.js',true)
23 xhr2.send()
24
25 xhr3=new XMLHttpRequest();
26 xhr3.open('get','https://cdn.bootcdn.net/ajax/libs/react/17.0.1/cjs/react-jsx-dev-runtime.development.js',true)
27 xhr3.send()
28 //以上是为了把数据先进行缓存起来
29
30 //onreadystatechange进行事件的获取，不使用的话数据获取不到
31 xhr2.onreadystatechange=function(){
32 if(xhr2.readyState==4 &&xhr2.status==200){
33 console.log(xhr2.responseText);
34 }
35 }
36 },3000)
37 }
38 </script>
39 </body>
40 </html>
