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- export type Maybe<T> = T | null | undefined
- /**
- * Used to test whether a `Maybe` typed value is `null` or `undefined`.
- *
- * When called, the given value's type is narrowed to `NonNullable<T>`.
- *
- * ### Example Usage:
- *
- * ```ts
- * const fn = (str: Maybe<string>) => {
- * if (!isNonNullable(str)) {
- * // typeof str = null | undefined
- * // ...
- * }
- * // typeof str = string
- * // ...
- * }
- * ```
- */
- export const isNonNullable = <T extends Maybe<unknown>>(val?: T): val is NonNullable<T> =>
- typeof val !== `undefined` && val !== null
|
