title: Uncaught SyntaxError: Unexpected string in my JavaScript
body: <p>I'm getting the Uncaught SyntaxError: Unexpected string error in my JavaScript and I honestly can't figure out what's wrong with the code.  I have looked at the similar questions, but I'm unable to find a solution.  The error is coming in the line highlighted with an asterisk below.</p>
  
  <pre><code>$("#items1").change(function () {
      if ($(this).data('options') === undefined) {
          $(this).data('options', $('#items2 option').clone());
      }
      var checkval = $(this).val();
  /* this line: */ var options = $(this).data('options').filter('[value='"+ checkval +"']');
      $('#items2').html(options);
  });
  </code></pre>
  
  <p>The code is taken from <a href="https://stackoverflow.com/questions/10570904/use-jquery-to-change-a-second-select-list-based-on-the-first-select-list-option">Use jQuery to change a second select list based on the first select list option</a></p>
  
  <p>I've added the extra quotes around the checkval to get rid of another error, this might be the problem, but if I change it, the other error returns.</p>