socket.io-client + react, where to connect to the server? - node.js

Question

I'm writing a very simple Nodejs app. I use React + Socket.io.
There's a root element which immediately renders another react component (you may wonder why I have this root element. The reason is that I want to be able to mount one of the two components after receiving a message from server, but for the start I render a preselected component).
In this root component , I define a socket in componentDidMount . Now the problem is that I want to pass this socket to all of the children (so they can listen and communicate with the server messages.) But if I connect to the server in componentDidMount of the root, during the rendering there is no socket as it's not connected yet and null will be passed to the child components.
'use strict';
var React = require('react');
var ioClient = require('socket.io-client');
var UsersList = require('./usersList');
var Game = require('./game');
var socket;
var Snake = React.createClass({
displayName: 'Snake',
propTypes: {},
getDefaultProps: function() {
return {};
},
mixins: [],
getInitialState: function() {
return ({
usersList: true,
game: false
});
},
componentWillMount: function() {
},
componentWillUnmount: function() {
this.socket.close();
},
componentDidMount: function() {
socket = ioClient.connect(); // this happens after render
},
render: function() {
var result = null;
if (this.state.usersList) {
result = <UsersList socket={socket}/> // therefore this one is passed as null
} else { //game : true
result = <Game socket={socket}/>
}
return (<div>
{result}
</div>)
}
});
module.exports = Snake;
'use strict';
var React = require('react');
var UsersList = React.createClass({
displayName: 'UsersList',
propTypes: {},
getDefaultProps: function() {
return {};
},
mixins: [],
getInitialState: function() {
return ({
usersList:[]
});
},
componentWillReceiveProps: function(){
},
componentWillMount: function() {
},
componentWillUnmount: function() {
},
componentDidMount: function(){
var socket = this.props.socket; // this one was passed into the component as null
socket.on('usersList', function(data){ // so this one returns an error
this.setState({
usersList: data.usersList
});
});
},
render: function() {
var users = [];
for (var i = 0 ; i < this.state.usersList.length ; i++){
users.push(<span>{this.state.usersList[i]}</span>);
}
return(<div>{users}</div>);
}
});
module.exports = UsersList;
So , now you may ask why I don't put io.connect() in componentWillMount or at the top of the file. Well , it doesn't work ! it returns this error : Cannot find property "protocol" ....
I cannot put it in render , componentWillMount , top of the file ...
Any idea on how to do this ?

Answer 1

You could continue to connect in componentDidMount. It will not be immediately available to the component's children, but then you could do something like this in the children:
componentDidUpdate(prevProps, prevState) {
if ( this.props.socket ) {
// do your connection logic here
}
}
This will ensure that the children immediately connect when the socket is first connected and available to them. Inside the if statement you could also verify that this.props.socket is not equal to prevProps.socket to prevent a redundant connection attempt.