Javascript create array into another array?

Question

I'm attempted to create a simple array, inside of another array.

Excuse me, as I'm a bit new to this, but I am attempting to insert the following:

"m1":["username"]

into a empty array named:

var mg = {}

So that it looks like this,

var mg = {"m1":["username"]}

I attempted to insert it like so,

function insertPlayer(mid, user){
mg.push(mid = [user]);
}

insertPlayer("m1", "username")

I was using the push function, but it seems to completely ignore me.

This is what I want:

With the function I was using, I'm getting this:

If I could get it the way I want, I can easily grab the list of usernames inside 'm1' by easily calling mg["m1"]

I'm sure there is an easy fix for this, but I just can't find it. I've been researching for about 30 minutes and decided to ask here. Thanks!

Answer 1

mg is an object, not an array, it does not have .push method.

Instead of mg.push(mid = [user]);, it should be mg[mid] = [user];.

After that, mg.mid is an array, if you want to add new user to it, you could use .push,

mg[mid].push(user);

So the function will like below:

// pass mg as a parameter is better than use it as a global in function
function insertPlayer(mg, mid, user){
  if (mg[mid]) {
     mg[mid].push(user);
  } else {
     mg[mid] = [user];
  }
}

Answer 2

var mg = {'m1': []};

Then try mg[mid].push(user); instead of mg.push(mid = [user]);