Happy Number.js

/*Write an algorithm to determine if a number is "happy".

A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy numbers.

Example: 19 is a happy number

1^2 + 9^2 = 82
8^2 + 2^2 = 68
6^2 + 8^2 = 100
1^2 + 0^2 + 0^2 = 1*/

/**
 * @param {number} n
 * @return {boolean}
 */
var isHappy = function(n) {
    sos = sumOfSquares(n)
    arr = [n]
    return isHappyHelper(sos,arr)
};

var isHappyHelper = function(curr,arr){
    sos = sumOfSquares(curr)
    if(sos == 1)
        return true
    if(arr.indexOf(sos) > -1)
        return false
    arr.push(sos)
    return isHappyHelper(sos,arr)
}

var sumOfSquares = function(n){
    arr = n.toString().split('').map(Number)
    sum = 0
    for(i=0; i<arr.length; i++)
        sum += Math.pow(arr[i],2)
    return sum
}