Function isOneOf

isOneOf<T, ArrayElement>(
element: T,
array: readonly ArrayElement[],
): element is ArrayElement
Returns whether array includes element.

Logically this is the same as array.includes(element), but is typed differently to accommondate the scenario in which array contains literal-type elements. See is-one-of for details.
Type Parameters
- T
  The type of element.
- ArrayElement
Parameters
- element: T
  The element to be determined whether it is included in array.
- array: readonly ArrayElement[]
  The array to be determined whether it includes element.
Returns element is ArrayElement
Whether whether array includes element.

See
is-one-of
- Defined in is-one-of.ts:81
isOneOf<T, SetElement>(
element: T,
set: Readonly<Set<SetElement>>,
): element is SetElement
Returns whether set includes element.

Logically this is the same as set.has(element), but is typed differently to accommodate the scenario in which set contains literal-type elements. See is-one-of for details.
Type Parameters
- T
  The type of element.
- SetElement
Parameters
- element: T
  The element to be determined whether it is included in set.
- set: Readonly<Set<SetElement>>
  The set to be determined whether it includes element.
Returns element is SetElement
Whether whether set includes element.

See
is-one-of
- Defined in is-one-of.ts:97
isOneOf<T, Element>(
element: T,
collection: readonly Element[] | Readonly<Set<Element>>,
): element is Element
A catch-all overload of the other two overloads. Check out the other two overloads for details.

This overload addresses the edge case in which collection may be either a Array or Set, and is expected to be used rarely.
Type Parameters
- T
- Element
Parameters
- element: T
- collection: readonly Element[] | Readonly<Set<Element>>
Returns element is Element
Example
```
for (const collection of [
  ["apple", "orange"] as const,
  new Set(["green", "red"] as const),
]) {
  isOneOf("sky", collection);
  // collection is of type readonly ["apple", "orange"] | Set<"green" | "red">
}
```
- Defined in is-one-of.ts:118

Function isOneOf

Type Parameters

Parameters

Returns element is ArrayElement

See

Type Parameters

Parameters

Returns element is SetElement

See

Type Parameters

Parameters

Returns element is Element

Example

Settings