determine if number is prime javascript code example

Example 1: prime numbers javascript

function isPrime(num) {
    for (let i = 2; i * i <= num; i++)
        if (num % i === 0)
          return false; 
    return num > 1;
}

Example 2: prime or not in javascript

function isPrime(num) {
  for(var i = 2; i < num; i++)
    if(num % i === 0) return false;
  return num > 1;
}