types-kit.isfalsy.md

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IsFalsy type

If T is a falsy value, return true, else return false.

Signature:

export type IsFalsy<T> = IfExtends<
  [T, never],
  true,
  IfExtends<
    [T, FalsyWithoutUnknown],
    IfExtends<[IsAny<T>, true], false, true>,
    IsUnknown<T>
  >
>

References: IfExtends, FalsyWithoutUnknown, IsAny, IsUnknown

Example

// Expect: true
type Foo = IsFalsy<never>
// Expect: false
type Foo = IsFalsy<true>