Stream command output to browser via websocket

command_output.pl

#!/usr/bin/env perl

use Mojolicious::Lite;
use 5.20.0;
use experimental 'signatures';

get '/' => {template => 'index'};

my $cmd = 'sleep 1; echo "hello world"; sleep 1; echo "yo peeps"';

websocket '/output' => sub ($c) {
  $c->send("Running command: $cmd\n");
  open my $output, '-|', $cmd or die "Couldn't spawn: $!";
  my $stream = Mojo::IOLoop::Stream->new($output);
  $stream->on(read => sub ($stream, $bytes) { $c->send({text => $bytes}) });
  my $sid = Mojo::IOLoop->stream($stream);
  $c->on(finish => sub { Mojo::IOLoop->remove($sid) });
};

app->start;

__DATA__

@@ index.html.ep
<pre id="log"></pre>
<script>
  var ws = new WebSocket('<%= url_for('output')->to_abs %>');
  var log = document.getElementById('log');
  ws.onmessage = function (event) { log.innerHTML += event.data };
</script>

I'm using this mechanism in https://github.com/jberger/Mojolicious-Plugin-TailLog