＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝ server.js 设置网络延时时间＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
//引用 express const { request, response, json } = require('express'); const express = require('express');
//创建应用对象 const app = express();
//创建路由规则， // request 是对请求报文的封装 // response 是对响应报文的封装 //app.all 可以接收任意类型的请求头 app.get('/cache', (request, response) => { //设置响应头，设置充许跨域 response.setHeader('Access-Control-Allow-Origin', '*'); setTimeout(() => { response.send('延时响应3秒.....'); }, 3000);
}) // 监听端口启动服务 app.listen(8000, () => { console.log('服务已经启动,8000端口监听中.......'); }) ============================index.html 设置超时时间与延时回调===============================
<!DOCTYPE html> <html lang="en">
<head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> <style> #result { width: 200px; height: 100px; border: solid 1px red; }
.abc { width: 200px; height: 100px; border: solid 1px pink; } </style> </head>
<body> <button>点我发送请求</button> <div class="abc"></div> <div id="result"></div> </body> <script> const btn = document.getElementsByTagName('button')[0]; const result = document.getElementById('result'); btn.addEventListener('click', function () { const xhr = new XMLHttpRequest(); xhr.timeout = 2000; xhr.ontimeout = function () { alert('网络导常，请稍后重试！！'); } xhr.open('GET', 'http://127.0.0.1:8000/cache?t=' + Date.now()); xhr.send(); xhr.onreadystatechange = function () { if (xhr.readyState == 4) { if (xhr.status >= 200 && xhr.status < 300) { result.innerHTML = xhr.response; } } } })
</script>
</html>