如何将 obj[key] 分配给数组

Question

I am trying to assign an empty obj with a variable [key] to an array and push the item to the array but for some reason it doesnt work properly. I wonder why the first item in the array is an empty string? How to correctly assign it to an array. Could any please advice? thank you!

let online = {};
let users = [];
let userInRoom =[];


 socket.on('join', ({ username, room, uUID }, cb) => {


    if(room in online){
        if(!online[room].includes(username)){
            online[room].push(username);
        }

    }else{
        online[room]=[...userInRoom, username];
    }

    console.log("online", online, "users", users);
   //---> the console result ==> online { general: [ '', 'jiojoij' ] } users [ 'jiojoij' ]

 });

I wonder why the first item in the array is an empty string? How to correctly assign it to an array.

Answer 1

Your logic seems a little confusing. What's the point of the userInRoom array if it's always empty? I would try something like:

if (!(room in online)) {
    online[room] = [];
}
if (!online[room].includes(username)) {
    online[room].push(username);
}