mdn-bug.js

console.log(Math.clz32(42424), clz(42424))

function clz(x) {
  // Let n be ToUint32(x).
  // Let p be the number of leading zero bits in 
  // the 32-bit binary representation of n.
  // Return p.    
  if (x == null || x === 0) {
    return 32;
  }
  // should be
  // return 31 - (Math.log(x >>> 0) / Math.LN2 | 0); // the "| 0" acts like math.floor
  return 31 - Math.log(x >>> 0) / Math.LN2 | 0; // the "| 0" acts like math.floor
}