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Using WebSockets with React

Murat Can Yüksel on September 12, 2021

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Vu • Sep 12 '21

I guess your code will create multiple instances of Websocket, you should put this in useEffect hook to avoid that

Víctor Salvans Montesó • Sep 12 '21

That's right. I will even go further and create a hook ( useWebsocket that uses useEffect internally) where you can pass the callback functions onopen and onmessage and returns a send function for instance or whatever you need from the hook.

Murat Can Yüksel • Sep 13 '21

Hey man, I wrote a reply to Vu's comment. Feel free to join the discussion :)

Vu • Sep 13 '21 • Edited

Every time the client receives new message => setBids called => component rerender => create new instance of Websocket => create new connection (1 request in devtools). This's not good, right :)))
This is my idea. You can check more in network tab in devtools and see the differents.


const apiCall = {
    event: 'bts:subscribe',
    data: { channel: 'order_book_btcusd' },
};
function App() {
    const [bids, setBids] = useState([0]);

    useEffect(() => {
        const ws = new WebSocket('wss://ws.bitstamp.net');
        ws.onopen = (event) => {
            ws.send(JSON.stringify(apiCall));
        };
        ws.onmessage = function (event) {
            const json = JSON.parse(event.data);
            try {
                if ((json.event == 'data')) {
                    setBids(json.data.bids.slice(0, 5));
                }
            } catch (err) {
                console.log(err);
            }
        };
        //clean up function
        return () => ws.close();
    }, []);
    const firstBids = bids.map((item, index) => (
        <div key={index}>
            <p> {item}</p>
        </div>
    ));

    return <div>{firstBids}</div>;
}

Murat Can Yüksel • Sep 13 '21

Hello, I have 4 components that I repeat the same method and it seems like each one waits its turn to display the data. I was wondering how to fix that, I guess you're taling about that? In my original code, I have useEffect in this manner :

 useEffect(() => {
    ws.onmessage = function (event) {
      const json = JSON.parse(event.data);
      try {
        if ((json.event = "data")) {
          dispatch(getOrderBookData(json.data));
        }
      } catch (err) {
        console.log(err);
      }
    };
    //clean up function
    return () => ws.close();
  }, []);

What should I do to overcome the problem you mentioned?

Evgeniy Tortumashev • Sep 13 '21

if ((json.event = "data")) {

Why "=", and not "==="?

dc • Sep 13 '21

Because he's not using a linter?
That's why he gets a lot of unfiltered events.

Murat Can Yüksel • Sep 13 '21 • Edited

Good question, that was some snippet I found while trying to figure out how to get started, and itseemed to work. I didn't even think about it. Will it cause any problems? It didn't so far...

Evgeniy Tortumashev • Sep 13 '21

This condition will always be true because the assignment operator is used instead of the comparison operator.

Murat Can Yüksel • Sep 13 '21

Gonna edit it (y)

Matthew Cale • Sep 12 '21

Clear, concise and useful! Thanks for sharing. As others have mentioned using the useEffect hook is likely the best spot for initializing WS, but it adds additional code so 🤷‍♀️. In any case really great work

ergisgjergji • Nov 23 '21

Sorry but this article has many technical errors.
Seems you've been aware about them yet you didn't correct the article.

Murat Can Yüksel • Jun 15 '22

True. I haven't touched websockets after writing this article though, worked on some other stuff and all. I'm thinking of trying to correct it as much as I can once I get the time to dive into websockets further.

Sandrin Joy • Mar 18 '22

I agree

Emmanuel Barroga • Sep 12 '21

Why use websocket and not socket.io? Just asking to exchange some dialog between the two.

Murat Can Yüksel • Sep 13 '21

To be honest, I'm not even sure what's the other one. I had 3 days to learn websockets and redux, so I went with that way.

What's the difference between the two? Why should I check socket.io?

Víctor Salvans Montesó • Sep 14 '21 • Edited

Websocket is the native api from your browser whereas socket.io does not implent the same api although it can use websocket under the hood if the browser support it, besides it has the server version that helps the backend keep the same interface with the client and add extra features as authentication , etc.

AntonioAllen77 • Sep 18 '21

Once the WebSocket server is created, we had to accept the handshake on receiving the request . dua to make someone call you

Anjali Chauhan • Oct 6 '22

thank you so much !
helpful for my assignment