Embed abcjs in vanilla forums pre elements if they are ABC

gistfile1.js

<script src="https://rawgit.com/paulrosen/abcjs/master/bin/abcjs_plugin_3.1.1-min.js"></script>

<script>
  abcjs_plugin_autostart = false;
  window.ABCJS.plugin.auto_render = false;
  ABCJS.plugin.hide_abc = true;
  ABCJS.plugin.render_options = {
    scale: 1,
    staffwidth:700,
    paddingtop: 0,
    paddingbottom: 0,
    paddingright: 0,
    paddingleft: 0,
}

$(document).ready(function(){
  function is_it_abc(elem) {
    if(window.ABCJS.plugin.getABCContainingElements(elem).length) return true;
    else return false;
  }

  if($("pre").length)
  {
    var tunes_code = $("pre");
			
    for(var $i=0; tunes_code[$i]; $i++)
    {               
      if(! is_it_abc($(tunes_code[$i]))) continue;

      var ws_strip="";
      var mystr="";

      ws_strip = $(tunes_code[$i]).text().split('\n');
      for(var aaa=0; ws_strip[aaa]; aaa++) { mystr+=ws_strip[aaa].trim() + "\n"; }

      $(tunes_code[$i]).text("%%staffsep 27pt\n"+mystr), //abctune

      $('<div id="abctune-' + $i + '" class="abctune-rendered"></div>').insertBefore(tunes_code[$i]);
      ABCJS.renderAbc(
        "abctune-"+$i, //container
        $(tunes_code[$i]).text(), //abctune
        {}, //parserParams
        { staffwidth: 620 }, //engraverParams
        { viewportHorizontal: true } //renderParams
      );
      $(tunes_code[$i]).hide();
    }
  }
})
</script>