前端学习（1422）：ajax获取服务器端的响应

// 引用expess框架
const express = require('express');
// 处理路径
const path = require('path');const bodyParser = require('body-parser');// 创建网站服务器
const app = express();
app.use(bodyParser.json());
app.get('/first', (req, res) => {res.send('hello geyao')
})
app.get('/responsdate', (req, res) => {res.send({ "name": "geyao" })
})
app.post('/post', (req, res) => {res.send(req.body);
})
app.get('/get', (req, res) => {res.send(req.query);
})
app.post('/json', (req, res) => {res.send(req.body);
})
app.get('/readystate', (req, res) => {res.send('hello');
})
app.use(express.static(path.join(__dirname)));
// 监听端口
app.listen(3000);
console.log('网站服务器启动成功, 请访问localhost')

ajax5.html

<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head><body><script>var xhr = new XMLHttpRequest();console.log(xhr.readyState);xhr.open('get', 'http://localhost:3000/readystate');console.log(xhr.readyState);xhr.onreadystatechange = function() {console.log(xhr.readyState);//if (xhr.readyState == 4) {console.log(xhr.responseText);}}xhr.send();</script>
</body></html>

运行结果