Calculating prime factors - exercism

prime-factors.js

var primeFactors = function () {}

primeFactors.prototype.for = function (num) {

    return calcPrimeFactor([], num)
}

var calcPrimeFactor = function (arr, num) {

    for (var i = 2; i <= num; i++) {

        if (num % i === 0) {
            arr.push(i)
            return calcPrimeFactor(arr, num / i);
        }
    }

    return arr;
}

module.exports = primeFactors;