notIncludes

The notIncludes() function checks that an array does not contain a given value and acts as a type guard to exclude this value from the typing.

Interactive example

Syntax

Classic signature

function notIncludes<
  GenericArrayValue extends unknown,
  const GenericNotIncludeValue extends RemoveFromUnion<
    Extract<GenericArrayValue, NotIncludeValue>,
    Exclude<NotIncludeValue, null | undefined>
  >,
>(
  input: readonly GenericArrayValue[],
  value: GenericNotIncludeValue,
): input is Exclude<
  GenericArrayValue,
  GenericNotIncludeValue
>[]

Curried signature

function notIncludes<
  GenericArrayValue extends unknown,
  const GenericNotIncludeValue extends RemoveFromUnion<
    Extract<GenericArrayValue, NotIncludeValue>,
    Exclude<NotIncludeValue, null | undefined>
  >,
>(
  value: GenericNotIncludeValue,
): (input: readonly GenericArrayValue[]) => input is Exclude<
  GenericArrayValue,
  GenericNotIncludeValue
>[]

Parameters

• input: Source array.
• value: Value whose absence you want to guarantee in the array.

Return value

A boolean. When true, TypeScript knows that the array does not contain value and removes the value from the element type.

See also

• includes - Checks for the presence of a value
• filter - Filters an array according to a predicate