oneOfGuard()

function oneOfGuard<T>(...guards): (data) => data is T[number]

Executes guards in order and returns true if any guard matches. The result type is a union.

Type Parameters

Type Parameter
T extends readonly unknown[]

Parameters

Parameter	Type	Description
...guards	{ [K in string | number | symbol]: Guard<T[K<K>]> }	any of these guard functions must match the data.

Returns

Function

a guard function that validates unions

Parameters

Parameter	Type	Description
data	unknown	data to be validated

Returns

data is T[number]

true if the data is in the specified union

Examples

Commonly used in discriminated unions:

const isResult = oneOfGuard([
 objectGuard({
   tag: equalsGuard('success')
 }),
 objectGuard({
   tag: equalsGuard('error')
  }),
])

When explicitly annotating oneOfGuard, provide a tuple of the union members as type argument:

const isId = oneOfGuard<[string, number]>(isString, isNumber)

Due to a limitation of TypeScript, it is not possible to write unionGuard<string | number>() or equalsGuard<'red' | 'green' | 'blue'>(). Therefore, it is generally recommended to omit the type arguments for union types and let TypeScript infer them.