Jquery下一个按钮不适用于图片库

Question

在我点击下一个按钮“两次”后，大图像只会更改为下一个图像。它适用于上一个按钮，但每当我重新加载页面时，它不适用于下一个按钮。

如果你能看看是什么问题，那就太好了，因为我已经尝试了很长时间来解决它，但无法解决。提前谢谢你。

<div > 
   <table id = "frame-table">
   <tr>
      <td id = "left1">
         <img src="http://www.vintagevictorian.com/kuba_arrow_button_left.png" alt = "left"/>
      </td>
      <td id = "right1">
         <img src="http://4vector.com/i/free-vector-kuba-arrow-button-set-clip-art_117492_Kuba_Arrow_Button_Set_clip_art_hight.png" alt = "right"/>
      </td>
  </tr>
  </table> 
  <img class="img" src="http://www.gravatar.com/avatar/3d561d41394ff0d5d0715b2695c3dcf0?s=128&d=identicon&r=PG" alt="Chania" width="204" height="236">  
</div>

<div id = "wrapper">
  <ul id = "portfolio">
     <li><img class="img-thumbnail" src="http://www.gravatar.com/avatar/3d561d41394ff0d5d0715b2695c3dcf0?s=128&d=identicon&r=PG" alt = "img"/></li>
     <li><img class="img-thumbnail" src="http://upload.wikimedia.org/wikipedia/commons/thumb/8/85/Smiley.svg/2000px-Smiley.svg.png" alt = "img"/></li>
     <li><img class="img-thumbnail" src="https://lh3.googleusercontent.com/-JE-Vccj5xwk/AAAAAAAAAAI/AAAAAAAAABg/aFghGr0aeYw/photo.jpg" alt = "img"/></li>
  </ul> 
  <button id="zoom" type="button" class="btn btn-info"> 
     <span class="glyphicon glyphicon-search"> Zoom </span> 
  </button> 
</div>

$(function(){
  var current_li =$("#portfolio li").first().parent();
  $("#right1").click(function(){
     if (current_li.is(":last-child")){ 
        var next_li = $("#portfolio li").first();
     } else{ 
        var next_li = current_li.next();
     }

    var next_src = next_li.children("img").attr("src");
    alert(next_src);
    $(".img").attr("src", next_src);
    current_li = next_li;
   });

   $("#left1").click(function(){ 
    if (current_li.is(":first-child")){
        var prev_li = $("#portfolio li").last();
    } else{
        var prev_li = current_li.prev();
    }   
    var prev_src = prev_li.children("img").attr("src");
    $(".img").attr("src", prev_src);
    current_li = prev_li;
   });
});

Answer 1

var current_li =$("#portfolio li").first().parent();

应该是

var current_li =$("#portfolio>li").first();

在本地测试并且正在运行。