getPrimes, isPrime

function getPrimes(max) {
    var sieve = [], i, j, primes = [];
    for (i = 2; i <= max; ++i) {
        if (!sieve[i]) {
            // i has not been marked -- it is prime
            primes.push(i);
            for (j = i << 1; j <= max; j += i) {
                sieve[j] = true;
            }
        }
    }
    return primes;
}


function isPrime (n)
{
    if (n < 2) return false;

    /**
     * An integer is prime if it is not divisible by any prime less than or equal to its square root
     **/

    var q = (int) Math.sqrt (n);

    for (var i = 2; i <= q; i++)
    {
        if (n % i == 0)
        {
            return false;
        }
    }

    return true;
}