Utils / isDefined

Function: isDefined()

isDefined<T>(value: undefined | T): value is T

Check whether a value is defined, meaning it is not undefined. This can be useful as a type guard, as for example, [1, undefined].filter(Boolean) does not always type-guard correctly.

Type Parameters

Type Parameter
T

Parameters

Parameter	Type
value	undefined | T

Returns

value is T

Example

import {isDefined} from 'ts-extras';
[1, undefined, 2].filter(isDefined);
//=> [1, 2]