/**
 * @param {number} n
 * @return {boolean}
 */
const reducer = (accumulator, currentValue) => accumulator + currentValue;

var getDigits = function(n) {
    let digits = [];
    let sNumber = n.toString();

    for (let i = 0, len = sNumber.length; i < len; i += 1) {
        digits.push(+sNumber.charAt(i));
    }

    return digits;
}

var square = function(n) {
    return n * n;
}

var isHappy = function(n) {
    let happy = false;

    // Special case for n == 1
    if (n == 1) {
        return true;
    }

    while (n != 1) {
        n = getDigits(n).map(x => square(x)).reduce(reducer);

        if (n == 1) {
            happy = true;
        }
    }

    return happy;
};