gistfile1.js

//Sieve of Eratosthenes
function findPrimesUpTo(value) {
	var primes = [];
	primes.push(false,false);
	for (var i = 2; i < value; i++) {
		primes.push(true);
	}

	for (var i = 2; i < Math.sqrt(value); i++) {
		if (primes[i] == true) {
			for (var j = Math.pow(i,2); j < value; j+=i) {
				primes[j] = false;
			}
		}
	}
	return primes;
}

console.log(findPrimesUpTo(100));