Is it a power of two

easypatternsBit manipulationMathJavaScript

A page allocator only caps sizes at exact powers of two, and a build report flags a size that slipped through.

Only non-negative sizes make sense here; anything negative is not a power of two.
Zero is not a power of two.
One counts: it is two raised to the zeroth power.

isPowerOfTwo(amount: int) → bool

Where you start

function isPowerOfTwo(amount) {
  
}

A power of two has exactly one bit set. Clearing the lowest set bit with n & (n - 1) turns it to zero.

Reference solution in JavaScript

function isPowerOfTwo(amount) {
  return amount > 0 && (amount & (amount - 1)) === 0;
}