• Verifies that the given value is not undefined. This especially helps with a .filter

    Type Parameters

    • T

    Parameters

    • x: undefined | T

    Returns x is T

    const values: (number | undefined)[] = [1, 2, undefined, 4];
    const definedValues: number[] = values.filter(isNotUndefined);
    // definedValues is now of type number[]