Perl NPH CGI streaming Comet events

nph-comet.pl

#!/usr/bin/perl
use warnings;
use strict;

sub chunk { sprintf "%x\x0D\x0A%s\x0D\x0A", length($_[0]), $_[0]; }

$|=1;

print "HTTP/1.1 200 Ok\x0D\x0A";
print "Content-Type: text/html\x0D\x0A";
print "Transfer-Encoding: chunked\x0D\x0A";
print "\x0D\x0A";
print chunk((' ' x 1024)."\n"); # enough blank space to break buffering
print chunk("<div id=\"counter\">0</div>\n");
for my $i (1..10) {
  print chunk("<script>document.getElementById('counter').innerHTML='$i';</script>\n");
  sleep 1;
}
print chunk('');

Example running here: https://www.ameriwether.com/cgi-bin/nph-comet.pl