菜单栏展开和收起效果(纯js)

2014年6月25日 15:36:29

需要关注的是:

1.用cookie保存用户当前点击的菜单项,不打扰后端代码

2.通过数学计算得到要显示和隐藏的div

3.点击事件是动态绑定到a标签上的,因此当dom加载完后,再执行js,也就是写在onload里

HTML如下:

 <h3 class="titleH3" id="101">aaaa</h3>
 <div class="subNav" id="1">
     <a href="#">1</a>
     <a href="#">2</a>
     <a href="#">3</a>
 </div>
 <h3 class="titleH3" id="102">bbbb</h3>
 <div class="subNav" id="2">
     <a href="#">11</a>
     <a href="#">22</a>
     <a href="#">33</a>
 </div>

js如下:

 function showhide()
 {
     //绑定a链接的点击事件
     //点击a链接的时候将id写进cookie
     var arrSubNav = document.getElementsByClassName('subNav');
     for (var i = 0; i < arrSubNav.length; i++) {
         var arrHref = arrSubNav[i].getElementsByTagName('a');
         for (var j = 0; j < arrHref.length; j++) {
             arrHref[j].onclick = function () {
                 var nodeParent = this.parentNode; //获取a链接所在的那个div块儿的id,注意,此处用this
                 var idParent = nodeParent.getAttribute('id');
                 document.cookie="userCheck="+idParent+";domain=***.***.com;path=/***"; //用cookie记录下用户当前的选择
             }
         }
     }

     //从cookie里取值,展开指定div
     userCheck = getUserCheckInfo();
     if (userCheck > 0) {
         for (var i = 0; i < arrSubNav.length; i++ ) {
             arrSubNav[i].style.display = 'none';
         }
         document.getElementById(userCheck).style.display = 'block';
     } else {
         document.getElementById('3').style.display = 'block';
     }

     //点击标题时展开其下的菜单
     var arrTitle = document.getElementsByClassName('titleH3');
     for (var i = 0; i < arrTitle.length; i++) {
         arrTitle[i].onclick = function () {
             var idTitle = this.getAttribute('id');
             var idSubNav = idTitle % 100; //根据title的id获取子菜单div的id

             for (var i = 0; i < arrSubNav.length; i++ ) {
                 arrSubNav[i].style.display = 'none';
             }
             document.getElementById(idSubNav).style.display = 'block';

         }
     };
 }

 function getUserCheckInfo()
 {
     var strCookie = document.cookie;
     //将多cookie切割为多个名/值对
     var arrCookie=strCookie.split("; ");
     var userCheck = '0';
     //遍历cookie数组，处理每个cookie对
     for(var i=0;i<arrCookie.length;i++) {
         var arr=arrCookie[i].split("=");
         if("userCheck"==arr[0]){
             userCheck=arr[1];
             break;
         }
     }
     return userCheck;
 }

变量名没有起好,userCheck应该为userChoice或者userSelected更恰当,他是用来保存用户点击的菜单的id的