unable to get socket data without page reload in react with below code

Question

Socket server in nodejs which sends data to client (server.js)-

const WebSocket = require('ws')
const wss = new WebSocket.Server({ port: 8000 })
wss.on('connection', ws => {
  ws.on('message', message => {
    console.log(`${message}`)
  })
  ws.send(JSON.stringify({
    type:'random_number2',
    interval: 2000, 
    take: 100, 
  }));
  ws.on('close', function() {
    console.log('closing connection');
  });
})

React front-end for receiving the socket data and display (socket.js)-

import React, { Component } from 'react';

const url = 'ws://localhost:8000';
const connection = new WebSocket(url);

class Socket extends Component {

  state = {
    response : ''
  }
  //componentWillMount() {
componentDidMount() {

    connection.onopen = () => {
      connection.send('Hello, Client is connected!!') 
    }

    setInterval( connection.onmessage = (message) => {
       this.setState({response : message.data});

        console.log("message");
        console.log(message);

        // if(this.state.response !== message.data){
        //   this.setState({response : message.data});
        // }

        console.log('message.data');  
        console.log(message.data);    
        },5000);

    connection.onclose = () => {
      console.log('disconnected');
      // automatically try to reconnect on connection loss
      }

    connection.onerror = err => {
        console.error(
            "Socket encountered error: ",
            err.message,
            "Closing socket"
        );
       // connection.close();
    };

  }

  render() {
    return (
      <div>
        Server Message
        {this.state.response}
      </div>
    );
  }
}

export default Socket;

From these 2 above files I am getting socket data on page reload but unable to get data without page reload I don't know why it is behaving like that in react App I have to receive data in bulk in my app that's why it is needed. I just created a demo for that if anyone know about socket in react than plz help.

saint · Accepted Answer · 2021-10-13 15:19:44Z

1

This is for anyone having the same problem. It's solved by declaring your WebSocket connection after the state as @Ritika has pointed out. like in hooks, inside useEffect.

useEffect(() => {
    // const connection = new WebSocket('ws://localhost:8000')
    //    Or if your are importing your connection from another file:
    const ws = connection();
   ....
  }, []);

answered Oct 13, 2021 at 15:19

saint

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Comments

Ritika · Accepted Answer · 2020-04-22 09:04:53Z

Problem Resolved with this code -

import React, { Component } from 'react';
import { w3cwebsocket as W3CWebSocket } from "websocket";

const url = 'ws://localhost:8000';

class Socket extends Component {

state = {
   response : ''
}

connection = new WebSocket(url);
componentDidMount() {
this.connection.onopen = () => {
  this.connection.send('Hello, Client is connected!!') 
}

this.connection.onmessage = (message) => {
    this.setState({response : message.data});    
}

this.connection.onclose = () => {
  console.log('disconnected');
}

this.connection.onerror = err => {
    console.error(
        "Socket encountered error: ",
        err.message,
        "Closing socket"
    );
   };
 }

render() {
return (
  <div>
    Socket Server Message
    {this.state.response}
  </div>
);
}
}

export default Socket;

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