用JavaScript、Nodejs写一个本地tcp服务，用于前端WebSocket调试

效果：

准备工作：

新建一个文件夹，在根目录安装依赖：

复制代码

npm install ws express

依赖介绍：

WS是一个轻量级、高效的WebSocket库，适用于Node.js环境。

express 是一个流行的Node.js Web应用程序框架。

新建server.js文件，和public文件夹，public下新建index.html：

server.js:

介绍：PORT为运行端口，看板地址为http://localhost: + PORT，连接地址为ws://localhost:+ PORT

javascript 复制代码

const express = require('express');
const WebSocket = require('ws');
const app = express();
const PORT = 3000;

// 创建 HTTP 服务
app.use(express.static(__dirname + '/public'));
const server = app.listen(PORT, () => {
  
});

// 创建 WebSocket 服务
const wss = new WebSocket.Server({ server });
let clients = [];

wss.on('connection', (ws) => {
  clients.push(ws);
  console.log(`New client connected. Total clients: ${clients.length}`);

  // 监听客户端消息
  ws.on('message', (message) => {
    console.log(`Received message: ${message}`);
    try {
      const parsedMessage = JSON.parse(message);
      if (parsedMessage.command === "ping") {
        ws.send(JSON.stringify({ command: "pong", data: "pong response" }));
      }
    } catch (e) {
      // 若消息不是 JSON 格式的字符串，直接处理为普通消息
      ws.send(`Echo: ${message}`);
    }
  });

  // 当客户端断开连接时，从列表中移除并记录信息
  ws.on('close', () => {
    clients = clients.filter((client) => client !== ws);
    console.log(`Client disconnected. Total clients: ${clients.length}`);
  });
});

// 定义推送消息的函数，广播给所有客户端
function broadcastMessage(message) {
  clients.forEach((client) => {
    if (client.readyState === WebSocket.OPEN) {
      client.send(message);
    }
  });
}

// 定义 API 接口用于前端推送消息
app.use(express.json());
app.post('/send', (req, res) => {
  const message = req.body.message;
  // 广播消息给所有客户端
  broadcastMessage(message);
  res.json({ status: 'Message sent' });
});

index.html:

介绍：可以根据自己测试的需要改变sendMessage发送的格式

html 复制代码

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>WebSocket Client</title>
  <style>
    #messages {
      border: 1px solid #ccc;
      padding: 10px;
      height: 200px;
      overflow-y: auto;
      margin-bottom: 10px;
    }
    .message {
      margin: 5px 0;
      padding: 5px;
    }
    .sent {
      color: green;
    }
    .received {
      color: black;
    }
    .status {
      color: blue;
    }
    .item{
        font-size: 12px;
        margin: 10px 0 ;
        display: flex;
        align-items: center;
    }
  </style>
</head>
<body>

  <div class="item">
    指令：
    <input type="text" id="command" placeholder="输入command" />
  </div>
  <div  class="item">
    数据：
    <input type="text" id="data" placeholder="输入data" />
  </div>
  <button onclick="sendMessage()">发送</button>
  <div id="messages"></div>
  <script>
    // WebSocket 连接
    const ws = new WebSocket("ws://localhost:3000");

    // 监听连接成功
    ws.onopen = () => {
      displayMessage("Connected to WebSocket server", 'status');
    };

    // 监听消息
    ws.onmessage = (event) => {
      const receivedData = event.data;
      displayMessage(receivedData, 'received');
    };

    // 发送消息
    function sendMessage() {
      const command = document.getElementById("command").value;
      const data = document.getElementById("data").value;
      if (command) {
        ws.send(JSON.stringify({
            command
        }));  // 发送消息到 WebSocket 服务器
        displayMessage(command, 'sent');  // 显示发送的消息
        // 通过 HTTP POST 向后端发送消息
        fetch('http://localhost:3000/send', {
          method: 'POST',
          headers: {
            'Content-Type': 'application/json'
          },
          body: JSON.stringify({ message: JSON.stringify({
            command,
            data:data ?? {}
        }) })
        }).then(response => response.json())
          .then(data => console.log(data));
      }
      document.getElementById("message").value = "";  // 清空输入框
    }

    // 显示消息
    function displayMessage(message, type) {
      const messagesDiv = document.getElementById("messages");
      const newMessage = document.createElement("div");
      newMessage.className = `message ${type}`;
      newMessage.textContent = `${type === 'sent' ? '发送' : type === 'received' ? '接收' : '状态'}: ${message}`;
      messagesDiv.appendChild(newMessage);
      messagesDiv.scrollTop = messagesDiv.scrollHeight;
    }
  </script>
</body>
</html>

使用：

根目录执行命令：node server

表单用浏览器访问：http://localhost:3000/

接收端WebSocket连接地址ws://localhost:3000也可以改成IP

接收端WebSocket我写过Android和uniapp的，可以参考下列文章：

https://blog.csdn.net/m0_49083276/category_12433687.html?fromshare=blogcolumn&sharetype=blogcolumn&sharerId=12433687&sharerefer=PC&sharesource=m0_49083276&sharefrom=from_linkhttps://blog.csdn.net/m0_49083276/category_12433687.html?fromshare=blogcolumn&sharetype=blogcolumn&sharerId=12433687&sharerefer=PC&sharesource=m0_49083276&sharefrom=from_link