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joplin notion extension/Web Development/nodejs/socket.io.md

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+socket.io
+
+- Using with http module
+  ```js
+	const PORT = process.env.PORT || 8080;
+
+	const httpServer = require("http").createServer();
+	const socketIO = require("socket.io");
+  
+	const io = socketIO(httpServer, {
+	  cors: { origin: "*" },
+	});
+
+	// when client connects to the server
+	io.on("connection", (socket) => {
+	  console.log(`user connected ${socket.id}`);
+	  io.emit("requestKey");
+
+	  // when listening to custom event named 'message'
+	  socket.on("message", (msgObjs) => {
+		// here using socket.broadcast.emit will send message to all client except the one who originally sent to server
+
+		for (let msgObj of msgObjs) {
+		  const id = msgObj.sid;
+		  io.to(id).emit("message", msgObj.message, socket.id);
+		}
+
+		// socket.broadcast.emit(
+		//   "message",
+		//   `${socket.id.substr(0, 2)} said ${message}`
+		// );
+
+		// to send to all including OP, use io.emit
+		// and for particular client use
+		// io.to(socket.id). emit("event", data);
+	  });
+	```
+	
+ 
+
+- Using with express
+  ```js
+	const express = require('express');
+	const app = express();
+	const socketIO = require('socket.io');
+
+	const PORT = process.env.PORT || 8080;
+	const keys = [];
+
+	// Serve your application on a specific route using Express
+	app.get('/', (req, res) => {
+	  res.sendFile(__dirname + '/index.html'); // Replace 'index.html' with your HTML file
+	});
+
+	// Create the HTTP server using Express
+	const server = app.listen(PORT, () => {
+	  console.log(`Server is running on port ${PORT}`);
+	});
+
+	// Initialize Socket.io by passing the HTTP server instance
+	const io = socketIO(server, {
+	  cors: { origin: "*" },
+	});
+
+	// Socket.io logic
+	io.on("connection", (socket) => {
+	  console.log(`User connected: ${socket.id}`);
+	  io.emit("requestKey");
+
+	  // ... (rest of your Socket.io logic)
+	});
+
+	```
+