TypeScript enum example

TypeScript enums work basically how’d you’d expect from any normal language:

enum LogLevel {
  info, debug, error, critical, none
}

These are numbered sequentially, so you can use them like so:

if (level >= currentLevel) {
  onLog(message);
}

You can also set the numbers, as you’d expect:

enum LogLevel {
  info = 7, debug, error, critical, none
}

If you do this, the subsequent numbers will be 8, 9, etc.

Some documentation I’ve seen¹ also recommends the use of these as flags, which is pretty neat as well (you see this a lot in code generated from other languages – e.g. ScalaJS or enscripten).

enum AnimalFlags {
    None           = 0,
    HasClaws       = 1 << 0,
    CanFly         = 1 << 1,
    EatsFish       = 1 << 2,
    Endangered     = 1 << 3
}

1. https://basarat.gitbooks.io/typescript/content/docs/enums.html [↩]