TypeScript · Senior · Question 3 of 75

What is `ToArray<string | number>` if `type ToArray<T> = T extends any ? T[] : never`?

✓Correct answer: string[] | number[]
2(string | number)[]
3never

Explanation

A conditional type over a "naked" type parameter distributes over a union: the condition is applied to each member separately. This is a distributive conditional type - Exclude and Extract are built on it.

Further reading

TS Handbook: Conditional Types ↗

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