isOptionalBoolean

isOptionalBoolean is a type guard that lets Typescript know that the variable passed in is either a boolean or undefined.

Parameters

candidate: unknown

Supply any variable to test if it’s either a boolean or undefined.

Returns

A type predicate for a boolean (candidate is boolean | undefined).

Examples

import { isOptionalBoolean } from '@revolutionarygamesco/common'

isOptionalBoolean(true) // true
isOptionalBoolean(false) // true
isOptionalBoolean(undefined) // true
isOptionalBoolean(1 + 1 === 2) // true
isOptionalBoolean('true') // false
isOptionalBoolean('undefined') // false
isOptionalBoolean(0) // false
isOptionalBoolean({ a: true }) // false