jquery selector doesn't work when dynamically append html

Question

I can dynamically append "select" control to DOM,after appending it to DOM,I wanna change the html content of the last "select"(the latest "select" added dynamically),but it failed...

(I cannot set options value in param_html,becuase I should set them by using ajax request later.)

<script>
    $(function(){
      var param_html = '<select class="params"></select>';
      $("input[value='+']").click(function(){
        $('#parameters').append(param_html);
          $('.params :last').html('<option>aaa</option><option>keyword in profile</option><option>last tweet</option>');
      });

    });
  </script>
  <div id="parameters">
    <input type="button" value="+">
    <select class="params"><option>1</option><option>2</option></select>
  </div>

any suggestion is appreciated.

Answer 1

take out the space between params and :last

$('.params:last').html('<option>aaa</option><option>keyword in profile</option><option>last tweet</option>');