小编Rav*_*v_g的帖子

$(document).ready(function() {
  // Optimalisation: Store the references outside the event handler:
  var $window = $(window);
  var $content = $('.content');
  var $cats = $('.span3');

  function checkWidth() {
      var windowsize = $window.width();
      if (windowsize < 767) {
        $content.insertBefore($cats);
      } else if (windowsize > 767) {
        $content.insertAfter($cats);
      }
    }
    // Execute on load
  checkWidth();
  // Bind event listener
  $(window).resize(checkWidth);
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<div class="content-entry">
  <div class="row">
    <div class="span3">span3</div>
    <div class="span9 content">span9/content</div>
  </div>
</div>