option-types

Utility types for options-related TypeScript definitions.

This package doesn't have any runtime code. It only contains types.

Motivation

Using exactOptionalPropertyTypes in TypeScript is great, except when you have a big object type with many optional properties. Manually adding undefined to every optional property type is annoying and error-prone.

Using conditional types and mapped types, we can automatically add undefined to every optional property type.

Types

Option<T>

Any type wrapped in Option can be assigned an undefined value. If the wrapped type is an object, its optional properties can also be assigned an undefined value. This type is recursive.

Options<T>

When an object type is itself required, but it contains optional properties, this type can be used to ensure that the optional properties can be assigned an undefined value. This type is recursive, so nested object types are also affected.

OptionalKeys<T>

Extract the keys of an object type that are optional. Note that a key is only considered “optional” if it was defined with a ? in the type definition.

ShallowOptions<T>

Ensure each optional property can be assigned an undefined value. Nested object types are not affected.