Using keyof typeof in Typescript

This combination is useful to take a JS object and turn it into a literal union type, based on the object's keys.

const dataObj = { x: 'foo', y: 1 };

type Data = typeof dataObj; // { x: string, y: number }
type DataKeys = keyof Data; // "x" | "y"

// or
type Keys = keyof typeof dataObj;

You can also get a type based on the object's values:

const dataObj = { x: 'foo', y: 1 };

type Values = (typeof dataObj)[keyof typeof dataObj];

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