Object.keys using numbers in typescript

All keys are strings in JavaScript – just use map:

const sizes: number[] = Object.keys(foo).map(Number);

This’ll only work for numeric strings – if it’s a European string involving decimals, for instance, it’ll be NaN, and that never ends well.


Or change either of your types:

const sizes: string[] = Object.keys(foo);


type Foo = { [key: string]: string };

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