Primes.js

<script>
(function (factors, primes) {
	var a_prime = 3, a_squared_prime = 9, maybe_prime = 3;
	function insertPrimeIntoSieve( factor ) {
    	/* This functions deliberately makes factors a sparse array */
		/* It will have nulls in the places which might be prime, */
		/* and primes in the places which are surely composites. */
		var where = factor;
		while( factors[where] )
			where += factor;
		/* If sparse arrays hurt your brain, you can pretend I had: */
		/* while( factors.length < where ) factors.push(0); */
		factors[ where ] = factor;
	}
	document.write("2 3 ");
	while( maybe_prime <= 999 ) {
		(function (factor) {
			maybe_prime += 2;
			if( factor ) {
				if( 0 != (maybe_prime % factor) )
					throw "Unexpected remainder.";
				insertPrimeIntoSieve( factor );
			} else if( maybe_prime < a_squared_prime ) {
				document.write( maybe_prime + " " );
				primes.push( maybe_prime );
			} else if( maybe_prime == a_squared_prime ) {
				insertPrimeIntoSieve( a_prime );
				a_prime = primes.shift();
				a_squared_prime = a_prime * a_prime;
			} else {
				throw "Critical math failure:  Programmer or compiler is innumerate.";
			}
			factors.shift();
		})(factors[0]);
	}
	document.writeln();
})([], []);
</script>