`Nullish`/`Nilable` type (like `Partial`, but accepts null)

[bvandercar-vt]

Type description + examples

Partial allows for all properties to be undefined. This type would do that, but also accept null.

export type Nullish<T> = { [K in keyof T]?: T[K] | null }

You may think "why not name it Nullable?" IMO, This would indicate only null, not also undefined. "Nullish" comes from the nullish coalescing operator ??-- "nullish" means "null or undefined"

Other possible names:

• NullablePartial (but Nullish is shorter and explains it)
• Nilable ("nil" can also commonly mean "both nul and undefined")

I also think that with this, it would make sense to add:

• IsNullish (or isNilable, if we go with that naming convention) - like IsOptional or IsNullable, but for both-- Returns a boolean for whether the given type includes null or undefined)
• NullishKeysOf / NilableKeysOf

Type source

No response

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