For-in loop in TypeScript always treats variable like a string

Question

This is something that has been bugging me for a while now. In TypeScript, if I define a for-in loop my variable is always treated as a string. Example:

for(var room in this.rooms) {
    room.placement.x = 52;
}

The room.placement.x will fail because it treats room as a string. this.rooms is actually a collection of Room objects, but room is not a Room... it's a string.

Is this a TypeScript version issue or something that is sticking around? It's highly frustrating.

Is there a way to define room so that TypeScript can treat it like a Room?

The definition of rooms is: private rooms: Room.Game.Room[];

It's an array of custom objects.

while this may be a duplicate question, the answer provided by Bruno is unique and is exactly what I needed. — BrianLegg, Aug 15 '16 at 15:49

score 14 · Accepted Answer · edited Feb 22 '23 at 19:16

14

If this.rooms is an array, the proper syntax is for ...of:

for (let room of this.rooms) {
    room.placement.x = 52;
}

for ... in iterates over the keys.

See this for more.

edited Feb 22 '23 at 19:16

Matthias Braun

32,039
22
142
171

answered Aug 15 '16 at 15:34

Bruno Grieder

28,128
8
69
101

This is exactly what I was looking for. Thank you. I will accept your answer when the timer lets me. – BrianLegg Aug 15 '16 at 15:42

For-in loop in TypeScript always treats variable like a string

1 Answers1