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Comment by reaktivo | Hacker News Reader

Since TS 3.4 you can have enum-like behaviour by using the `as const` annotation on object and array literals.

    const types = ['x', 'y', 'z'] as const;
    const a: typeof types[number] = 'a'; // not ok
    const b: typeof types[number] = 'z'; // ok

Not to be confused with `const enum` which act more like a preprocessor and emits in the value at compile time.

    const enum Directions { Up, Down, Left, Right }
    console.log(Directions.Left)
    // emits js file with console.log(2)