WebSocket: How to automatically reconnect after it dies
This worked for me with setInterval
, because client connection can be lost.
ngOnInit(): void {
if (window.location.protocol.includes('https')) {
this.protocol = 'wss';
}
this.listenChanges();
}
listenChanges(): void {
this.socket = new WebSocket(`${this.protocol}://${window.location.host}/v1.0/your/url`);
this.socket.onmessage = (event): void => {
// your subscription stuff
this.store.dispatch(someAction);
};
this.socket.onerror = (): void => {
this.socket.close();
};
this.socket.onopen = (): void => {
clearInterval(this.timerId);
this.socket.onclose = (): void => {
this.timerId = setInterval(() => {
this.listenChanges();
}, 10000);
};
};
}
Don't forget to call clearInterval
when the socket has been opened.
This isn't explicitly a react question but here is a react style answer:
TLDR: You can use setInterval
to periodically check the websocket connection status and try to re-connect if the connection is closed. https://developer.mozilla.org/en-US/docs/Web/API/WebSocket/readyState
class TestComponent extends React.Component {
constructor(props) {
super(props);
this.state = {};
this.connect = this.connect.bind(this);
}
componentDidMount() {
this.interval = setInterval(this.connect, 1000);
}
componentWillUnmount() {
if (this.ws) this.ws.close();
if (this.interval) clearInterval(this.interval);
}
connect() {
// https://developer.mozilla.org/en-US/docs/Web/API/WebSocket/readyState
if (this.ws === undefined || (this.ws && this.ws.readyState === 3)) {
this.ws = new WebSocket(`ws://localhost:8080`);
this.ws.onmessage = (e) => {
console.log(JSON.parse(e.data));
};
}
}
render() {
return <div>Hey!</div>;
}
}
Here is what I ended up with. It works for my purposes.
function connect() {
var ws = new WebSocket('ws://localhost:8080');
ws.onopen = function() {
// subscribe to some channels
ws.send(JSON.stringify({
//.... some message the I must send when I connect ....
}));
};
ws.onmessage = function(e) {
console.log('Message:', e.data);
};
ws.onclose = function(e) {
console.log('Socket is closed. Reconnect will be attempted in 1 second.', e.reason);
setTimeout(function() {
connect();
}, 1000);
};
ws.onerror = function(err) {
console.error('Socket encountered error: ', err.message, 'Closing socket');
ws.close();
};
}
connect();