ua.pl

use Mojo::Base -strict;
use Mojo::UserAgent;

my $ua = Mojo::UserAgent->new;

# Random UserAgent header
$ua->on(start => sub {
  my ($ua, $tx) = @_;
  $tx->req->headers->user_agent(join '',
    map { ('a' .. 'z')[rand 26] } 1 .. 10);
});

# Detect Mojolicious
$ua->on(start => sub {
  my ($ua, $tx) = @_;
  $tx->res->content->on(body => sub {
    say 'Yay, Mojolicious!'
      if shift->headers->header('Server') =~ /mojolicious/i;
  });
});

# Test JSON
$ua->on(start => sub {
  my ($ua, $tx) = @_;
  $tx->res->on(finish => sub {
    my $res = shift;
    $res->error('This is no JSON!')
      if $res->headers->content_type =~ /json/i && !defined($res->json);
  });
});

my $tx = $ua->get($ARGV[0] // 'mojolicio.us');
say $tx->success ? $tx->res->body : ('Error: ', $tx->error);