010.html

<html>
<head>
<title>JavaScript</title>
</head>
<body>


<script language="JavaScript" type="text/javascript">

// 6k+/-1 method
function plusMinus6k(x) {
	var ceil;
	
	if (x < 4) {
		if (x == 1) { return false; }
		return true;
	}
	
	if (x < 9) { return true; }
	if (x % 3 == 0) { return false; }
	
	ceil = Math.ceil(Math.sqrt(x));
	
	for (var i = 5; i <= ceil; i += 6) {
		if (x % i == 0) { return false; }
		if (x % (i + 2) == 0) { return false; }
	}
	return true;
}


function sumOfPrimesUnder(x) {
	var sum = 2;
	
	if (x < 2) { return 0; }
	
	for (var i = 3; i < x; i += 2) {
		if (plusMinus6k(i)) {
			sum += i;
		}
	}
	return sum;
}


</script>
</body>
</html>