How to properly render heavy web socket stream in React? - reactjs

Question

I currently have something like this:
const socket = require('socket.io-client')('https://example.com');
(....)
// Listen to the channel's messages
socket.on('m', message => {
// this is a Redux action that updates the state
this.props.updateTrades(message);
});
The reducer looks like this:
case actions.UPDATE_TRADES:
return {
...state,
trades: [
...state.trades,
action.trade
]
};
I've tried not using redux and just to the following:
socket.on('m', message => {
this.setState(state => {
if (state.trades.length > 99) {
state.trades.splice(0, 1);
}
return {
trades: [
...state.trades,
message
]
});
});
I don't need to keep increasing my trades array. I'm happy just to keep around 100 items or so...
Socket is sending around 15 messages / second.
My problem is: I can't seem to render the messages in real-time! It just freezes. I guess the stream is just too fast? Any suggestions?
Thanks in advance!

Answer 1

The thing is to do the minimum possible and when the trades change only draw what has change and not all of the elements of the array.A technique that I use is to keep a cache map of already drawn obj, so in the render method I only render the new incoming elements.
Take a look at https://codesandbox.io/s/wq2vq09pr7
class RealTimeList extends React.Component {
constructor(props) {
super(props);
this.cache = [];
}
renderRow(message, key) {
return <div key={key}>Mesage:{key}</div>;
}
renderMessages = () => {
//let newMessages=this,props.newMessage
let newElement = this.renderRow(this.props.message, this.cache.length);
this.cache.push(newElement);
return [...this.cache];
};
render() {
return (
<div>
<div> Smart List</div>
<div className="listcontainer">{this.renderMessages()}</div>
</div>
);
}
}
class App extends React.Component {
constructor(props) {
super(props);
this.state = { message: "hi" };
}
start = () => {
if (this.interval) return;
this.interval = setInterval(this.generateMessage, 200);
};
stop = () => {
clearTimeout(this.interval);
this.interval = null;
};
generateMessage = () => {
var d = new Date();
var n = d.getMilliseconds();
this.setState({ title: n });
};
render() {
return (
<div className="App">
<h1>Hello CodeSandbox</h1>
<h2>Start editing to see some magic happen!</h2>
<button onClick={this.start}> Start</button>
<button onClick={this.stop}> Stop</button>
<RealTimeList message={this.state.message} />
</div>
);
}
}
The class RealTime List have a cache of elements.Let me know if this helps.

Answer 2

It's probably not a good idea to try to render all of the changes. I think you should try rendering them in batches so you only update once every few seconds, that should help.