Check Evil Number in JavaScript

function popCount(n) {
  let count = 0;
  let x = n >>> 0;
  while (x !== 0) {
    count += x & 1;
    x >>>= 1;
  }
  return count;
}

function isEvil(n) {
  if (n < 0) {
    return false;
  }
  return popCount(n) % 2 === 0;
}

const number = 15;
if (isEvil(number)) {
  console.log(`${number} is an Evil Number.`);
} else {
  console.log(`${number} is not an Evil Number.`);
}

function isEvilNonNeg(num) {
  let ones = 0;
  while (num > 0) {
    if (num % 2 === 1) {
      ones += 1;
    }
    num = Math.floor(num / 2);
  }
  return ones % 2 === 0;
}

console.log("Evil numbers in the range 1 to 10:");
let line = "";
for (let i = 1; i <= 10; i++) {
  if (isEvilNonNeg(i)) {
    line += i + " ";
  }
}
console.log(line.trim());

function popcountKernighan(n) {
  let ones = 0;
  while (n) {
    n &= n - 1;
    ones += 1;
  }
  return ones;
}

function isEvilKernighan(n) {
  if (n < 0) {
    return false;
  }
  return popcountKernighan(n) % 2 === 0;
}

for (const n of [15, 7, 0, 3]) {
  const label = isEvilKernighan(n) ? "evil" : "odious";
  console.log(`${n}: ${label} (ones=${popcountKernighan(n)})`);
}