TypeScript · Middle · Question 51 of 75

Why does `Omit<Circle | Square, 'id'>` lose the discriminated union?

type DistributiveOmit<T, K extends PropertyKey> = T extends any ? Omit<T, K> : never;

✓Correct answer: Omit uses keyof of the whole union (only common keys); a distributive version applies it to each member
2Omit doesn't work with unions at all
3It removes id only from the first member

Explanation

keyof (A | B) contains only shared keys, so member-specific properties disappear. The conditional type distributes over the union.

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