Javascript error

Hi,

Thanks for this plugin, really works in reducing page load time.

But I’m receiving an JS error message when the FOUC removal option is activated:

TypeError: $ is not a function

If the affected Javascript inline code is removed from the core.php file (line 94), it doesn’t seem to affect anything.

<script type="text/javascript" >
  $(document).ready(function() {
    loadeddocument();
  });
  </script>

Is this snippet necessary for something else? I just would like to check.

https://www.ads-software.com/plugins/speed-booster-pack/