Utility Types

Utility types are built-in helpers that transform existing types.

Like cookie cutters for shapes you already have.

Instead of rewriting shapes by hand, you make Partial, Pick, Omit, and more.

That fits forms, patches, and API payloads.

Partial and Required

Partial makes every property optional.

Optional means each blank may be skipped.

Required does the opposite. Every property must be there.

Pick and Omit

Pick<T, K> keeps selected keys.

Omit<T, K> removes them.

Handy for public shapes that hide secret fields.

Record

Record<Keys, Value> builds an object type.

Keys come from a union. Values share one type.

That fits maps and lookup tables.

A lookup table is a dictionary from key to value.

ReturnType and Parameters

These helpers pull types from existing functions.

You stay in sync without copying signatures by hand.

A signature is the list of inputs and the output type.

Why utilities help

Change the source type once.

Derived types follow.

Derived means made from another type.

Less copy paste. Fewer mismatches.

Utility types keep related shapes in sync. Change the source once. Derived types follow.