What does Split return? type Split = S extends `${infer Head}/${infer Rest}` ? [Head, ...Split ] : [S];

TypeScript · Senior · Question 9 of 75

What does `Split<'a/b/c'>` return?

type Split<S extends string> =
  S extends `${infer Head}/${infer Rest}`
    ? [Head, ...Split<Rest>]
    : [S];

✓Correct answer: ['a', 'b', 'c']
2string[] (a general type)
3['a/b/c'] (no parsing)

Explanation

infer inside a template literal parses the string: Head captures the part before the first /, Rest the remainder. Recursion and variadic tuples assemble the result. This is how route params like /users/:id are typed.

What does `Split<'a/b/c'>` return?

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What does Split<'a/b/c'> return?

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What does `Split<'a/b/c'>` return?