Happy Number:

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.

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

No file or test entry point is named. First inspect the repository's JavaScript exercise layout to find where the function belongs, then implement the stated happy-number behavior and verify the 19 example plus a number that enters a non-1 cycle.

Written by the indexing model from the issue text.