Type Signature · #35 · 2026-05-09
Inside the `if` block, what is the type of `animal`?
TypeScript ·Difficulty 1/3
How to play
Read the TypeScript snippet and pick the correct type from four choices. Think about inference, narrowing, and utility types. Press 1–4 or click to answer.
type Fish = { swim: () => void };
type Bird = { fly: () => void };
function move(animal: Fish | Bird) {
if ('swim' in animal) return animal;
}
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Press 1 through 4, or tap a numbered choice, to answer. Back to hub