https://leetcode.com/problems/power-of-two/

powerOfTwo.js

/**
 * @param {number} n
 * @return {boolean}
 */
// Idea: if it's a power of two, there must
// be only one bit set. 
var isPowerOfTwo = function(n) {
    if(n<=0) return false; // it could be negative. Return false;
    n&=(n-1); // unset the lowest set bit
    return n === 0; // If there are any bits left, return false. Otherwise
    // it's a power of two!
};

// turned into golf because why not...
var golf = (n) => n<=0 ? false : (n&(n-1)) === 0;