服务端
//1.引入（利用express框架） const express = require('express'); // const { request } = require('http'); //2.创建应用对象 const app = express(); //3.创建路由规则 //response 是对响应报文的封装 //request 是对请求报文的封装 app.all('/server',(request,response)=>{ //设置响应头,设置允许跨域 response.setHeader('Access-Control-Allow-Origin','*'); response.setHeader('Access-Control-Allow-Headers','*'); //设置响应 response.send('HELLO AJAX GET'); }); //all表示可以接收任意类型的请求 app.all('/json-server',(request,response)=>{ //设置响应头,设置允许跨域 response.setHeader('Access-Control-Allow-Origin','*'); //设置响应头(所有信息的头信息都可以接收) response.setHeader('Access-Control-Allow-Headers','*'); //响应一个数据 const date = { name: 'chen' }; //对对象进行字符串转换 let str = JSON.stringify(date); //设置响应体 response.send(str); }); //针对IE缓存 app.get('/ie',(request,response)=>{ //设置响应头,设置允许跨域 response.setHeader('Access-Control-Allow-Origin','*'); response.setHeader('Access-Control-Allow-Headers','*'); //设置响应 response.send('HELLO IE'); }); //针对延时响应 app.get('/delay',(request,response)=>{ //设置响应头,设置允许跨域 response.setHeader('Access-Control-Allow-Origin','*'); response.setHeader('Access-Control-Allow-Headers','*'); //设置响应体 setTimeout(()=>{ response.send('延时响应'); },3000) }); //4.监听端口并启动服务 app.listen(8080,()=>{ console.log("服务已经启动,8080 端口监听中..."); });
请求端
缓存问题
<!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>缓存问题</title> <style> #result{ width: 200px; height: 100px; border: solid 1px #258; } </style> </head> <body> <button>点击发送请求</button> <div id="result"></div> <script> const btn = document.getElementsByTagName('button')[0]; const result = document.querySelector('#result'); btn.addEventListener('click',function(){ const xhr = new XMLHttpRequest(); xhr.open("GET",'http://127.0.0.1:8080/ie?t='+Date.now()); xhr.send(); xhr.onreadystatechange = function(){ if(xhr.readyState === 4){ if(xhr.status >= 200 && xhr.status<300){ result.innerHTML = xhr.response; } } } }) </script> </body> </html>
超时与网络问题
<!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>IE缓存问题</title> <style> #result{ width: 200px; height: 100px; border: solid 1px #258; } </style> </head> <body> <button>点击发送请求</button> <div id="result"></div> <script> const btn = document.getElementsByTagName('button')[0]; const result = document.querySelector('#result'); btn.addEventListener('click',function(){ const xhr = new XMLHttpRequest(); //超时设置2s xhr.timeout = 2000; //超时回调 xhr.ontimeout =function(){ alert("网络异常,请稍后重试!"); } //网络异常回调 xhr.onerror = function(){ alert("你的网络似乎出了一些问题!"); } xhr.open("GET",'http://127.0.0.1:8080/delay'); xhr.send(); xhr.onreadystatechange = function(){ if(xhr.readyState === 4){ if(xhr.status >= 200 && xhr.status<300){ result.innerHTML = xhr.response; } } } }) </script> </body> </html>
请求问题
<!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>请求问题</title> </head> <body> <button>点击发送</button> <button>点击取消</button> <script> const btns = document.querySelectorAll('button'); let x = null; btns[0].onclick = function(){ x = new XMLHttpRequest(); x.open("GET",'http://127.0.0.1:8080/delay'); x.send(); } //abort取消请求 btns[1].onclick = function(){ x.abort(); } </script> </body> </html>
重复请求问题
<!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>重复请求问题</title> </head> <body> <button>发送请求</button> <script> const btns = document.querySelectorAll('button'); let n = null; //标识变量 let isSending = false;//是否正在发送AJAX请求 btns[0].onclick = function(){ if(isSending) n.abort(); n = new XMLHttpRequest(); //修改 标识变量 isSending = true; n.open("GET",'http://127.0.0.1:8080/delay'); n.send(); n.onreadystatechange = function(){ if(n.readyState === 4){ //修改标识变量 isSending = false; } } } </script> </body> </html>
