本文實例講述了js實現簡潔大方的二級下拉菜單效果代碼。分享給大家供大家參考。具體如下：
這是一款簡潔大方的二級下拉菜單，菜單的顏色自己根據需要重新定義吧，這里僅給大家提供一種制作二級菜單的思路，整體效果看上去相當實用，下拉導航菜單也是大家比較常用的。
運行效果截圖如下：
在線演示地址如下：
http://demo.VeVB.COm/js/2015/js-simple-2level-show-down-menu-codes/
具體代碼如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><title>簡潔大方的二級下拉菜單</title><meta http-equiv="content-type" content="text/html;charset=gb2312"><style type="text/css">*{margin:0;padding:0;font-style:normal;font-family:宋體;}body{text-align:center;font-size:14px;}#content{margin:0 auto;width:600px;}#content #nav{background:#006400;height:32px;margin-top:10px;}#content #nav ul{list-style:none;}#content #nav ul li{float:left;width:100px;line-height:32px;position:relative;}#nav div{width:100px;position:absolute;left:0px;padding-bottom:0px;background:#006400;float:left;height:0;overflow:hidden;}#content #nav li .a{text-decoration:none;color:#00CD00;line-height:32px;display:block;border-right:1px solid #009800;}#nav div a{text-decoration:none;color:#00CD00;line-height:26px;display:block;}#nav div a:hover{background:#005400;}</style></head><body><div id="content"> <div id="nav"> <ul id="supnav"> <li><a href="#" class="a">菜單項1</a> <div> <a href="#">菜單測試1</a> <a href="#">菜單測試1</a> <a href="#">菜單測試1</a> </div> </li> <li><a href="#" class="a">菜單項2</a> <div> <a href="#">菜單測試2</a> <a href="#">菜單測試2</a> <a href="#">菜單測試2</a> </div> </li> <li><a href="#" class="a">菜單項3</a> <div> <a href="#">菜單測試3</a> <a href="#">菜單測試3</a> <a href="#">菜單測試3</a> <a href="#">菜單測試3</a> <a href="#">菜單測試3</a> </div> </li> <li><a href="#" class="a">菜單項4</a> <div> <a href="#">菜單測試4</a> <a href="#">菜單測試4</a> <a href="#">菜單測試4</a> </div> </li> <li><a href="#" class="a">菜單項5</a> <div> <a href="#">菜單測試5</a> <a href="#">菜單測試5</a> <a href="#">菜單測試5</a> <a href="#">菜單測試5</a> </div> </li> <li><a href="#" class="a">菜單項6</a> <div> <a href="#">菜單測試6</a> <a href="#">菜單測試6</a> <a href="#">菜單測試6</a> </div> </li> </ul> </div></div><script type="text/javascript">var supnav=document.getElementById("supnav");var nav=document.getElementById("nav");var btns=document.getElementsByTagName("li");var subnavs=nav.getElementsByTagName("div");var paddingbottom=20;var defaultHeight=0;function drop(obj,ivalue){ var a=obj.offsetHeight; var speed=(ivalue-obj.offsetHeight)/8; a+=Math.floor(speed); obj.style.height=a+"px";}window.onload=function(){ for(var i=0;i<btns.length;i++){ btns[i].index=i; btns[i].onmouseover=function(){ var osubnav=subnavs[this.index]; var sublinks=osubnav.getElementsByTagName("a"); if(osubnav.firstChild.tagName==undefined){ var itarheight=parseInt(osubnav.childNodes[1].offsetHeight)*sublinks.length+paddingbottom; }else{ var itarheight=parseInt(osubnav.firstChild.offsetHeight)*sublinks.length+paddingbottom; } clearInterval(this.itimer); this.itimer=setInterval(function(){drop(osubnav,itarheight);},30); } btns[i].onmouseout=function(){ var osubnav=subnavs[this.index]; clearInterval(this.itimer); this.itimer=setInterval(function(){drop(osubnav,defaultHeight);},30); } }}</script></body></html>希望本文所述對大家的javascript程序設計有所幫助。
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