javascript - 可以计算 div id 中特定 div 类的数量吗？

Question

有以下脚本:

    var CurrentPageTop = 0;
    var PageHeight = 496;
    var TotalPages = 9;
    var CurrenPage = 1;
    function Slide( control, panel ){



            if ( control.name == "SlideDown" ){

                    if ( (CurrenPage >= 1) && (CurrenPage <= TotalPages-1) ){
                            CurrenPage++;
                            CurrentPageTop =  ( CurrentPageTop - PageHeight );
                    }
            }

            if ( control.name == "SlideUp" ){

                    if ( (CurrenPage > 1) && (CurrenPage <= TotalPages) ){
                            CurrenPage--;
                            CurrentPageTop = (CurrentPageTop + PageHeight);
                    }
            }       

            var PanelScroller = document.getElementById(panel);
            PanelScroller.style.top = CurrentPageTop + 'px';

            var CurrenPageId = document.getElementById("CurrenPageId");
            CurrenPageId.innerHTML = "Page " + CurrenPage + " of 9";
    }

页面上附带一个图片库:

      <table cellpadding="0" cellspacing="0">
    <tr>
            <td>
                    <div class="SlidingPanel">
                            <div id="PanelScroller">
                                    <div class="Page">
         <a href="surf/1.jpg" rel="shadowbox[Surf]"><img src="i/gal/g1.jpg"></a>
          </div>

如何将其设置为在一页上有多个实例？

有些画廊有 9 张图片，有些有 6 张，等等。

有没有办法统计<div class="Page">的数量在<div id="PanelScroller">内？

我想避免为 3 个不同的画廊使用此脚本的 3 个略有不同的实例。我只是无法理解它，因为我是新手。

Answer 1

function number_of_elements_with_class_name(class_name) {
    var elements = getElementsByClassName(class_name);
    var count = 0;
    for(var i in elements) {
        count++;
    }
    return count;
}