keyof and typeof

keyof T is the union of a type's property names: keyof { a: number; b: string } is "a" | "b". In a type position, typeof value gives you the type of a real value. Together they derive types from your data instead of writing them twice, so the types update automatically when the data changes.

How it reads

• typeof palette copies the object's shape into a type
• keyof turns that shape into "dusk" | "dawn" | "night"
• Add a color to the object and ColorName grows by itself

Cloud tip: Object.keys always returns string[]. Cast it with as (keyof T)[] only when you know the object has no extra keys.