Given an integer n, return true if it is a power of three. Otherwise, return false. An integer n is a power of three, if there exists an integer x such that n == 3x.

isPowerOfThree.js

/**
 * @param {number} n
 * @return {boolean}
 */
var isPowerOfThree = function(n) {
    // Powers of 3 are always positive (3^0 = 1, 3^1 = 3, etc.)
    if (n < 1) return false;

    // Keep dividing n by 3 as long it's it's divisible
    while (n % 3 === 0) {
        n /= 3; // Divide n by 3
    }

    // If we end up with 1, it means n was a power of 3
    return n === 1;
};