A snippet of JavaScript code could look like this:

var hiddenBox = $( "#banner-message" );
$( "#button-container button" ).on( "click", function( event ) {
  hiddenBox.show();
});

The following information was provided by Derek Davenport on the Webguides mailing list 4/3/15.

jQuery is normally called $ (as it is without the theme when you’re editing), but with the theme it’s jqbs or jQuery. $ is undefined. So everywhere it says $, change it to jQuery.

There’s other ways to fix this which you can read about here: https://api.jquery.com/jquery.noconflict/.