以 express 为列子
proxy.js
const express = require('express');
const { createProxyMiddleware } = require('http-proxy-middleware');
const app = express();
app.use(express.static(__dirname + '/'));
app.use('/api', createProxyMiddleware({ target: 'http://localhost:4000', changeOrigin: true }));
module.exports = app;i ndex.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>
<script src="https://unpkg.com/axios/dist/axios.min.js"></script>
</head>
<body>
<p>3000端口的页面</p>
<p>data</p>
<script>
(async () => {
// 调用函数的函数体
// axios.defaults.withCredentials = true;
let response = await axios.get("/api/users");
console.log(response.data);
document.writeln(`response + ${JSON.stringify(response.data)}`);
})();
</script>
</body>
</html>
通过代理服务器，我们就避免了跨域问题
浏览器----》 start.js--->app.js
/api ---> localhost:4000/