Ajax 获取进度和中断请求

HTML加入一些内容方便看效果和做交互：

<div><p>当前传输进度：<span id="progress">0%</span></p><button id="send">发送</button><button id="btn">中断</button>
</div>

JavaScript 核心代码：

// 发送请求document.getElementById('send').addEventListener('click', function () {const xhr = new XMLHttpRequest()xhr.open('GET', 'http://localhost:9001/test')xhr.onreadystatechange = function () {if (xhr.readyState === 4 && xhr.status === 200) {console.log(xhr.responseText)}}// 获取进度xhr.addEventListener('progress', function (e) {console.log(e)const percent = (e.loaded / e.total) * 100document.getElementById('progress').textContent = percent.toFixed(2) + '%'})// 点击按钮中断请求document.getElementById('btn').addEventListener('click', function () {console.log('中断请求')xhr.abort()})xhr.send()})

这里我自己弄了个简单的node服务器做测试：

const express = require('express')
const app = express()//创建get请求
app.get('/test', (req, res) => {res.setHeader('Content-Type', 'application/json;charset=utf-8')res.setHeader('Access-Control-Allow-Origin', '*')// 读取txt文件const fs = require('fs')const data = fs.readFileSync('resData.txt', 'utf-8')res.json({code: 200,message: "请求成功",data})})
//端口号9001
app.listen(9001)
console.log('server is running at http://localhost:9001')

这里resData.txt是要返回的文本内容，因为要数据凉够大才方便查看进度，所以用了文本文件

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效果：