DOM事件探秘-5-1-编程挑战-原创手记-慕课网

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>下拉菜单</title>
    <style type="text/css">
body,ul,li{ margin:0; padding:0; font-size:13px;}
ul,li{list-style:none;}
#divselect{width:186px; margin:80px auto; position:relative; z-index:10000;}
#divselect cite{width:150px; height:24px;line-height:24px; display:block; color:#807a62; cursor:pointer;font-style:normal;
padding-left:4px; padding-right:30px; border:1px solid #333333; 
/*background:url(xjt.png) no-repeat right center;*/}
#divselect ul{width:184px;border:1px solid #333333; background-color:#ffffff; position:absolute; z-index:20000; margin-top:-1px; display:none;}
#divselect ul li{height:24px; line-height:24px;}
#divselect ul li a{display:block; height:24px; color:#333333; text-decoration:none; padding-left:10px; padding-right:10px;}
    </style>
   <script type="text/javascript">
window.onload=function(){
    var box=document.getElementById('divselect'),
        title=box.getElementsByTagName('cite')[0],
        menu=box.getElementsByTagName('ul')[0],
        as=box.getElementsByTagName('a'),
        index=-1;

    // 点击三角时
    title.onclick=function(event){
      // 执行脚本
      menu.style.display="inherit";
      if(event.stopPropagation){
        event.stopPropagation();
      }else{
        event.cancelBubble=true;
      }

    };

   // 滑过滑过、离开、点击每个选项时
      // 执行脚本
      for(var i = 0;i<as.length;i++){
        as[i].onmouseover=function(){
          this.style.backgroundColor="#ccc";
        };
        as[i].onmouseout=function(){
          this.style.backgroundColor="#fff";
        };
        as[i].onclick = function(){
          title.innerHTML = this.innerHTML;
        };
      }
//按键部分 上38下40回车13
      document.onkeyup=function(event){
        var keycode = event.keyCode;
        if(keycode===38){
          if(index===-1){
            index=as.length-1;
          }else{
            as[index].style.backgroundColor="#fff";
            if(index===0){
              index=as.length-1;
            }else{
              index--;
            }
          }
          as[index].style.backgroundColor="#ccc";
        }else if(keycode===40){
          if(index===-1){
            index=0;
          }else{
            as[index].style.backgroundColor="#fff";
            if(index===as.length-1){
              index=0;
            }else{
              index++;
            }
          }
          as[index].style.backgroundColor="#ccc";
        }else if(keycode===13){
          if(index!=-1){
            title.innerHTML=as[index].innerHTML;
            index=-1;
            menu.style.display="none";
          }
        }

      };
   // 点击页面空白处时
       // 执行脚本
    document.onclick=function(){
      menu.style.display="none";
    };
 };
   </script>
</head>
<body>
    <div id="divselect">
      <cite>请选择分类</cite>
      <ul>
         <li id="li"><a href="javascript:;" selectid="1">ASP开发</a></li>
         <li><a href="javascript:;" selectid="2">.NET开发</a></li>
         <li><a href="javascript:;" selectid="3">PHP开发</a></li>
         <li><a href="javascript:;" selectid="4">Javascript开发</a></li>
         <li><a href="javascript:;" selectid="5">Java特效</a></li>
      </ul>
    </div>
</body>
</html>