A Javascript version: Prime Number Generator in Javascript

Generates prime numbers from 2 to 1,000,000 using Eratosthenes’ prime number sieve. Why? Why not.

PERL source code is available:

#!/usr/bin/perl #Generates prime numbers from 2 to 1,000,000 using Eratosthenes’ prime number sieve. Why? Why not. #prints out NPH allowing the script to output as it generates and prevents 30 sec timeout use CGI qw(:standard -nph); print "Content-type: text/plain\n\n"; $| = 1; print "<title>Prime Number Generator</title>\n"; $tt = time(); $limit = 1000000 ; $limitSqrt = int(sqrt($limit)); print "Prime Numbers up to $limit<p>\n\n"; # $notprime{$num} = undef $num is prime # $notprime{$num} = 1 $num is not prime #calculate and print primes up to sqrt($limit) #we are actually generating a list of non primes by adding each number (up to sqrt($limit) ) repeatedly until we reach $limit. #all sums will not be prime for($num=2; $num <= $limitSqrt; ++$num) #for($num=2; $num <= $limit; ++$num) { $sum = $num; if ($notprime{$num}) { #this number is not a prime so it's factors's multiples have already been checked off next; } else { #this number has not yet been marked 'not prime' so it must be prime as we have already checked for all possible lesser factors print "$num\n" } while ($sum < $limit) #add $num repeatedly up to limit. all sums will not be prime. same as all multiples of $num { $sum = $sum + $num; $notprime{$sum} = 1; #not prime } } #all non primes have been found up to $limit at this point. #print already calculated primes after sqrt($limit) for($num=$limitSqrt + 1; $num < $limit; ++$num) { if (!$notprime{$num}) { print "$num\n" } } print "<p><p>\n\nSeconds: " ; print time() - $tt; print "\n\n" ; 1;