All

This snippet returns true if the predicate function returns true for all elements in a collection and false otherwise. You can omit the second argument fnif you want to use Booleanas a default value.

    const all = (arr, fn = Boolean) => arr.every(fn);

    all([4, 2, 3], x => x > 1); // true
    all([1, 2, 3]); // true