javascript實現的三級下拉導航選單

antzone發表於2017-04-01
原文網址 : https://www.softwhy.com/article-5427-1.html
JavaScript

本章節介紹一下分享一段使用原生javascript實現的三級下拉導航選單效果。

在實際應用中更為常見的是二級導航選單，但是三級導航的選單的出現頻率也並不少，當然實現更為複雜一些。

下面就是程式碼例項，需要的朋友可以進行一下參考。

程式碼例項:

[HTML] 純文字檢視 複製程式碼
<!DOCTYPE html>
<html>
<head>
<meta charset=" utf-8">
<meta name="author" content="http://www.softwhy.com/" />
<title>螞蟻部落</title>
<style type="text/css">
*{
  margin:0;
  padding:0;
  border:0;
}
li{list-style: none;}
.clearfix:after{
  content:" ";
  display:block;
  height:0;
  clear:both;
  visibility:hidden;
}
.clearfix{display: inline-block;}
a:link{
  color:#000;
  text-decoration:none;
}
a:visited{
  color:#000;
  text-decoration:none;
}
a:hover{
  color:#000;
  text-decoration:none;
}
.menu{
  width:778px;
  height:26px;
  background:#fff;
  margin:0 auto;
}
.menusel{
  float:left;
  width:100px;
  position:relative;
  height:25px;
  background:#ddd;
  line-height:25px;
  margin-left:1px;
  *margin-left:0px;
  _margin-left:-1px;
}
.menusel h2{font-size:12px;}
.menusel a{
  display:block;
  text-align:center;
  width:100px;
  border:1px solid #a4a4a4;
  height:25px;
  border-bottom:1px solid #a4a4a4;
  position:relative;
  z-index:2;
}
.menusel a:hover{
  border:1px solid #a4a4a4;
  border-bottom:1px dashed #eeeeee;
  position:relative;
  z-index:2;
  height:25px;
}
.ahover a{
  border-bottom:1px dashed #eeeeee;
  background:#eeeeee;
}
.position{
  position:absolute;
  z-index:1;
}
.menusel ul{
  width:125px;
  background:#eee;
  border:1px solid #a4a4a4;
  margin-top:-1px;
  position:relative;
  z-index:1;
  display:none;
}
.menusel .block{
  display:block;
}
.typeul li{
  border-bottom:1px dashed #a4a4a4;
  width:125px;
  position:relative;
  float:left;
}
.typeul li a{
  border:none;
  width:125px;
}
.typeul li a:hover{
  border:none;
  background:#ddd;
}
.typeul{
  margin-left:0;
}
.typeul ul{
  left:125px;
  top:0;
  position:absolute;
}
.fli{
  margin-left:-1px;
  border-left:#eeeeee solid 1px;
}
.menusel .lli{
  border:none;
}
</style>
</head>
<body>
<div class="menu">
  <div id="menu1" class="menusel">
    <h2><a href="/">選單1</a></h2>
    <div class="position">
      <ul class="clearfix typeul">
        <li><a href="http://www.jb51.net">選單選項1-2</a></li>
        <li> <a href="#">選單選項1-2</a>
          <ul>
            <li class="fli"><a href="#">選單選項1-2-1</a></li>
            <li class="lli"><a href="#">選單選項1-2-2</a></li>
          </ul>
        </li>
        <li><a href="http://www.jb51.net">選單選項1-2</a></li>
        <li class="lli"><a href="#">選單選項1-2</a></li>
      </ul>
    </div>
    <!-- position -->
  </div>
  <!-- menusel -->
  <div id="menu2" class="menusel">
    <h2><a href="#">選單2</a></h2>
    <div class="position">
      <ul class="clearfix typeul">
        <li><a href="#">選單選項2-2</a></li>
        <li><a href="#">選單選項2-2</a>
          <ul>
            <li class="fli"><a href="#">選單選項2-2-1</a></li>
            <li class="lli"><a href="#">選單選項2-2-2</a>
              <ul>
                <li class="fli"><a href="#">選單選項2-2-1</a></li>
                <li class="lli"><a href="#">選單選項2-2-2</a> </li>
              </ul>
            </li>
          </ul>
        </li>
        <li><a href="#">選單選項2-2</a></li>
        <li class="lli"><a href="#">選單選項2-2</a></li>
      </ul>
    </div>
    <!-- position -->
  </div>
  <!-- menusel -->
  <div id="menu3" class="menusel">
    <h2><a href="#">選單3</a></h2>
    <div class="position">
      <ul class="clearfix typeul">
        <li><a href="#">選單選項3-2</a></li>
        <li><a href="#">選單選項3-2</a>
          <ul>
            <li class="fli"><a href="#">選單選項3-2-1</a></li>
            <li class="lli"><a href="#">選單選項3-2-2</a>
              <ul>
                <li class="fli"><a href="#">選單選項3-2-1</a></li>
                <li class="lli"><a href="#">選單選項3-2-2</a>
                  <ul>
                    <li class="fli"><a href="#">選單選項3-2-1</a></li>
                    <li class="lli"><a href="#">選單選項3-2-2</a></li>
                  </ul>
                </li>
              </ul>
            </li>
          </ul>
        </li>
        <li><a href="#">選單選項3-2</a></li>
        <li class="lli"><a href="#">選單選項3-2</a></li>
      </ul>
    </div>
    <!-- position -->
  </div>
  <!-- menusel -->
</div>
<!-- menu -->
<script type="text/javascript">  
 for(var x = 1; x < 4; x++) {  
   var menuid = document.getElementById("menu"+x);  
   menuid.num = x;  
   type();  
 }  
 function type(){  
   var menuh2 = menuid.getElementsByTagName("h2");  
   var menuul = menuid.getElementsByTagName("ul");  
   var menuli = menuul[0].getElementsByTagName("li");  
   menuh2[0].onmouseover = show;  
   menuh2[0].onmouseout = unshow;  
   menuul[0].onmouseover = show;  
   menuul[0].onmouseout = unshow;  
   function show(){  
     menuul[0].className = "clearfix typeul block"  
   }  
   function unshow(){  
     menuul[0].className = "typeul"  
   }  
   for(var i = 0; i < menuli.length; i++){  
     menuli[i].num = i;  
     var liul = menuli[i].getElementsByTagName("ul")[0];  
     if(liul){  
       typeshow()  
     }  
   }  
   function typeshow(){  
     menuli[i].onmouseover = showul;  
     menuli[i].onmouseout = unshowul;
   }  
   function showul(){  
     menuli[this.num].getElementsByTagName("ul")[0].className = "block";  
   }  
   function unshowul(){  
     menuli[this.num].getElementsByTagName("ul")[0].className = "";  
   }  
}  
</script>
</body>
</html>

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