TypeScript · Senior · Question 38 of 75

What does `keyof (A | B)` return if `A = { id; name }` and `B = { id; price }`?

✓Correct answer: 'id'
2'id' | 'name' | 'price'
3never

Explanation

A union value can be any of its members, so only common keys are safe to access. keyof (A & B) gives the union of all keys. To distribute keyof over union members, use a conditional type: T extends any ? keyof T : never.

What does `keyof (A | B)` return if `A = { id; name }` and `B = { id; price }`?

Explanation

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What does keyof (A | B) return if A = { id; name } and B = { id; price }?

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What does `keyof (A | B)` return if `A = { id; name }` and `B = { id; price }`?