Happy Number

Description

Write an algorithm to determine if a number n 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.

Return True if n is a happy number, and False if not.

Example: 

Input: 19
Output: true
Explanation: 
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1

Solution(javascript)

/**
 * @param {number} n
 * @return {boolean}
 */
var isHappy = function(n) {
    const getNum = (x) => x.toString().split("").reduce((acc, num) => acc + Number(num) * Number(num), 0)
    let slow = getNum(n)
    let fast = getNum(slow)
    while(slow !== fast) {
        if(fast === 1) {
            return true
        }
        slow = getNum(slow)
        fast = getNum(fast)
        fast = getNum(fast)
    }
    return fast === 1
};