algorithmpool/src/algopool/math/isPowerOfTwo.js

A pool of algorithms and data-structures for geeks

export function isPowerOfTwo(number) {
    // 1 (2^0) is the smallest power of two.
    if (number < 1) {
        return false;
    }

    /*
     * Powers of two in binary look like this:
     * 1: 0001
     * 2: 0010
     * 4: 0100
     * 8: 1000
     *
     * Note that there is always exactly 1 bit set. The only exception is with a signed integer.
     * e.g. An 8-bit signed integer with a value of -128 looks like:
     * 10000000
     *
     * So after checking that the number is greater than zero, we can use a clever little bit
     * hack to test that one and only one bit is set.
     */
    return (number & (number - 1)) === 0;
}