Type Alias IsTypeInList<T, L>

IsTypeInList: L extends [infer F, ...(infer R)]
? If<Equals<T, F>, true, false> extends true ? true : IsTypeInList<T, R>
: L extends [infer F] ? If<Equals<T, F>, true, false> : false

Test whether a type can be found within a list of types.

Type Parameters

T
A type to search for
L extends any[]
A list of types

Remarks

This will recursively check each type in the list L to see if it matches type T. If returns true as soon as a match is found and false if no matches are found or if the list is empty.

Example

type TrueIsFound = IsTypeInList< true, [ 1, 'no', true ] >;      // true
type TrueIsNotFound = IsTypeInList< true, [ 1, 'no', false ] >;  // false
type ListIsEmptySoFalse = IsTypeInList< true, [] >;              // false

Type Alias IsTypeInList<T, L>

Type Parameters

Remarks

Example

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