find prime number function javascript es6

//#Source https://bit.ly/2neWfJ2 
const isPrime = num => {
  const boundary = Math.floor(Math.sqrt(num));
  for (var i = 2; i <= boundary; i++) if (num % i === 0) return false;
  return num >= 2;
};

console.log(isPrime(11));
console.log(isPrime(17));
console.log(isPrime(8));