first commit

.gitignore

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+node_modules

index.js

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+const express = require("express");
+const { createServer } = require("http");
+const { Server } = require("socket.io");
+const cors = require('cors');
+
+const app = express();
+
+app.use(cors()); 
+var roomid='';
+const httpServer = createServer(app);
+const io = new Server(httpServer, { 
+    cors:{
+        origin:"http://localhost:3000",
+        methods:["GET","POST"],
+        credentials:true
+    }
+});
+
+io.on("connection", (socket) => {
+    console.log("server connected");
+    roomid=socket.id;
+    socket.on("beginPath", ({ x, y}) => {
+      console.log("beginPath - room:", roomid);
+      io.to(roomid).emit("beginPath", { x, y });
+    });
+
+    socket.on("drawLine", ({ x, y}) => {
+       console.log("drawLine - room:", roomid);
+      io.to(roomid).emit("drawLine", { x, y });
+    });
+
+      socket.on('changeConfig', (arg) => {
+        io.to(roomid).emit('changeConfig',arg)
+      });
+
+      socket.on('changeactiveitem', (arg) => {
+        io.to(roomid).emit('changeactiveitem', arg)
+      });
+
+      socket.on('changeactionitem', (arg) => {
+        io.to(roomid).emit('changeactionitem', arg)
+      });
+
+      socket.on('joinroom', ({ room }) => {
+        console.log('User joined room:', room);
+        roomid=room;
+        socket.join(room);
+        io.to(room).emit('userJoined', { userId: socket.id });
+      })
+});
+
+app.get('/', (req, res) => {
+    res.send('hello world')
+});
+httpServer.listen(4000, () => {
+    console.log("server is running at port 4000");
+});