<div class="nav">  <ul>   <li><a>網站首頁</a></li>   <li><a>關于我們</a></li>   <li><a>產品中心</a></li>   <li><a>成功案例</a></li>   <li><a>聯系我們</a></li>   <li><a>在線留言</a></li>  </ul> </div> <script type="text/javascript" src="js/jquery.min.js"></script> <script type="text/javascript">  //jQuery time  var parent, ink, d, x, y;  $(".nav ul li a").click(function (e) {   parent = $(this).parent();   //create .ink element if it doesn't exist   if (parent.find(".ink").length == 0)    parent.prepend("<span class='ink'></span>");   ink = parent.find(".ink");   //incase of quick double clicks stop the previous animation   ink.removeClass("animate");   //set size of .ink   if (!ink.height() && !ink.width()) {    //use parent's width or height whichever is larger for the diameter to make a circle which can cover the entire element.    d = Math.max(parent.outerWidth(), parent.outerHeight());    ink.css({ height: d, width: d });   }   //get click coordinates   //logic = click coordinates relative to page - parent's position relative to page - half of self height/width to make it controllable from the center;   x = e.pageX - parent.offset().left - ink.width() / 2;   y = e.pageY - parent.offset().top - ink.height() / 2;   //set the position and add class .animate   ink.css({ top: y + 'px', left: x + 'px' }).addClass("animate");  }) </script>