http协议
http协议特点：
- 无状态协议
- 每个请求是独立的
- 单双工通信，且服务器无法主动给客户端发信息
- http协议受浏览器同源策略影响
http实现双向通信方法:
- 轮询
- 长轮询
- iframe流
- sse EventSource
websocket协议
websocket协议:
- 全双工协议
- 支持跨域
- 支持多种数据格式
客户端
<!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>// 服务端提供websocket服务const ws = new WebSocket("ws://localhost:3000");ws.onopen = () => {console.log("客户端连接成功");// 给服务端发送消息ws.send("hi server");};// 监听服务端数据ws.onmessage = function (ev) {console.log("服务端：", ev.data);};</script></body>
</html>
服务端
import http from "http";
import express from "express";
import { WebSocketServer } from "ws";const app = express();
const server = http.createServer(app); // http服务
const wss = new WebSocketServer({ server });wss.on("connection", (ws) => {console.log("服务端连接成功");// 给客户端发消息ws.send("hi client");// 监听客户端数据ws.on("message", (msg) => {console.log("客户端：", msg.toString());});
});server.listen(3000);
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