网页中点击增加按钮

效果：

HTML：

        <table border="1" width="100%" class="table_a" style="display:none" id="gallery-tab-table">
            <tr><input type="hidden" name="gallery_act" value="gallery_tab"></tr>
            <tr>
                <th>
                    <span style="cursor: pointer" onclick="add_item()">[+]</span>
                    <label>商品相册</label>
                </th>
                <td>
                    <input type="file" name="goods_pics[]" id="goods_pics_0"/>
                    <div id="goods_pics_div_0">
                        <img src="" alt="" id="goods_pics_img_0" height="100">
                    </div>
                </td>
            </tr>
            <script type="text/javascript">
                $(function () {
                    new uploadPreview({
                        UpBtn: "goods_pics_0",
                        DivShow: "goods_pics_div_0",
                        ImgShow: "goods_pics_img_0"
                    })
                })
            </script>
        </table>

javascript:

        <script type="text/javascript">
            var num = 1;
            function add_item() {
                var s = "<tr><th><span style='cursor: pointer' onclick='$(this).parent().parent().remove()'>[-]</span><label>商品相册</label></th><td><input type='file' name='goods_pics[]' id='goods_pics_"
                    + num + "'/><div id='goods_pics_div_" + num + "'><img src='' alt='' id='goods_pics_img_" + num + "' height='100'></div></td></tr>";
                $('#gallery-tab-table').append(s);

                new uploadPreview({
                    UpBtn: "goods_pics_" + num,
                    DivShow: "goods_pics_div_" + num,
                    ImgShow: "goods_pics_img_" + num
                });
                num++;
            }
        </script>