无法使用一个套接字模块将变量名从一个节点模块发送到另一个节点模块，以将其用作聊天应用程序的房间名称

Question

I am able to get the room name from user but as I use module.exports in another file to retrieve it shows undefined . This might be because it is asynchronous.

//roomcheck.js

var nsp = io.of("/gameroom");
nsp.on('connection', (socket) => {
socket.on('check', (data) => {
    if (rm.includes(data)) {
        roomname = data;
        console.log(roomname);
        console.log("Room exist!!!");
        socket.emit('success', 'room already made');
});

module.exports=roomname;

//userpage.js

var r=require('roomcheck.js');
console.log(r.roomname);

Expected - roomname entered by user.

My output - undefined

Answer 1

• Firstly, you are right, it is becouse it is asynchronous
• Secondly you have set the module.exports itself to be the roomname, which means that module.exports is not an object it is the string itself

So basically r is module.exports

If I were you I would make module.exports and object that has an onRoomCheck function to which I could pass a callback to

Example code:

//roomcheck.js

var roomCheckCallback = ()=>{};
var nsp = io.of("/gameroom");
nsp.on('connection', (socket) => {
socket.on('check', (data) => {
    if (rm.includes(data)) {
        roomname = data;
        console.log(roomname);
        roomCheckCallback({roomname:roomname,exists:true});
        console.log("Room exist!!!");
        socket.emit('success', 'room already made');
    } else { roomCheckCallback({roomname:null,exists:false}); }
});
module.exports = {}
module.exports.onRoomCheck = function(callback){
    roomCheckCallBack = callback;
}

//userpage.js

var r=require('roomcheck.js');
r.onRoomCheck( (room)=> { console.log(room.roomname) } );

Answer 2

The solution to this is to make a delay by setTimeout function In roomcheck.js

setTimeout(()=>{
module.exports=roomname;
},1000);

This provides a delay of 1 second and gives roomcheck.js to get the roomname and then export it