No. 246 · August 29, 2026 · Hard

Entries

Implement `ObjectEntries<T>` so it produces the union of `[key, value]` pairs — the type-level shape of `Object.entries`. Each pair must keep its own key matched to its own value.

Puzzle

Par 4

Puzzle

object-entries.ts

type ObjectEntries<T> = ???

type ObjectEntries<T> = ???

Stroke 1 of 4Not run yet

Replace ??? — your solution is checked against the cases below. Tab indents; press Escape then Tab to move focus out.

Checks

ObjectEntries<{ a: string; b: number }>—
→ ['a', string] | ['b', number]
ObjectEntries<{ x: 1 }>—
→ ['x', 1]
ObjectEntries<{}>—
→ never

How a check is judged Exact type equality, not assignability — an intersection is not the same as the flattened object.

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Uses

Mapped types Partial Pick Omit Record Mapped types Make Omit catch typos Flatten an intersection Require at least one property Make two prop shapes mutually exclusive