includesAll Checks if all the elements in values are included in arr. Use Array.prototype.every() and Array.prototype.includes() to check if all elements of values are included in arr. const includesAll = (arr, values) => values.every(v => arr.includes(v)); includesAll([1, 2, 3, 4], [1, 4]); // true includesAll([1, 2, 3, 4], [1, 5]); // false