Best type for Game object Index Signatures? about typed-screeps HOT 3 CLOSED

I've noticed that changing the hash type does negatively affect loops. When iterating over, e.g., Game.rooms, we know that all of the elements will not be undefined. But this is not expressed by the type { [roomName: string]: Room | undefined }, which describes elements which can be a Room or undefined in all contexts, in lookups, iteration, etc.

Fixing it requires temporarily overriding the type, which is pretty ugly:

// Find all controlled and claimed rooms
const claimedRooms = _.filter(Game.rooms as {[roomName: string]: Room}, (room) => {
  return room.controller && room.controller.my;
});

(The type of claimedRooms is then {[roomName: string]: Room} which then kind of goes back to the original problem if I want to do lookups on this new hash.)

I also found this discussion about pretty much the same thing in the TpyeScript repo:

microsoft/TypeScript#9235
microsoft/TypeScript#7140 (comment)

So I don't think my approach in #108 is really workable anymore. I don't really want to model a hash with undefined elements. I think what I'm really looking for is to just change the type of the hash lookup function. But I don't think it's really possible in TypeScript right now.

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You can use https://www.typescriptlang.org/tsconfig#noUncheckedIndexedAccess

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Can we close this?

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