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JavaScript implements display and hiding of drop-down menu_javascript skills
JavaScript implements display and hiding of drop-down menu_javascript skills
In this article, we will use JavaScript script to display and hide the drop-down menu. The knowledge we need to use JavaScript methods to implement is:
1) JS events: onmouseover mouse passing event and onmouseout mouse leaving event.
2) JS basic syntax: Use the function keyword to define functions.
3) DOM programming: getElementsByTagName() method.
Then the next step is our production process:
1) Hide the secondary menu: Set the CSS style to hide the secondary menu.
2) Write the showsub() function to display the submenu: use getElementsByTagName to obtain the secondary menu items; set the secondary menu display through style.display.
3) Write the hidesub() function of the hidden submenu: use getElementsByTagName to obtain the secondary menu items; set the secondary menu to be hidden through style.display.
4) Add mouse events: Add mouse events to the first-level menu with a second-level menu, and call the showsub()/hidesub() function to realize the display and hiding of the second-level menu when the mouse passes through the first-level menu.
5) Do browser compatibility testing, at least five browsers. IE7,8,9, Firefox, Google, 2345 browser, etc.
Rendering:
HTML code:
<span style="font-size:18px;"><!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> <meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> <title>下拉菜单</title> <!--引入的外部CSS样式文件--> <link rel="stylesheet" type="text/css" href="style.css" /> <!--引入的外部JS脚本文件--> <script type="text/javascript" src="script.js"></script> </head> <body> <div id="nav" class="nav"> <ul> <li><a href="#">网站首页</a></li> <li onmouseover="showsub(this)" onmouseout="hidesub(this)"><a href="#">课程大厅</a> <ul> <li><a href="#">JavaScript</a></li> <li><a href="#">jQuery</a></li> <li><a href="#">Ajax</a></li> </ul> </li> <li onmouseover="showsub(this)" onmouseout="hidesub(this)"><a href="#">学习中心</a> <ul> <li><a href="#">视频学习</a></li> <li><a href="#">案例学习</a></li> <li><a href="#">交流平台</a></li> </ul> </li> <li><a href="#">经典案例</a></li> <li><a href="#">关于我们</a></li> </ul> </div> </body> </html> </span>
External CSS style sheet style.css file code:
<span style="font-size:18px;">/*CSS全局设置*/
*{
margin:0;
padding:0;
}
.nav{
background-color:#EEEEEE;
height:40px;
width:450px;
margin:0 auto;
}
ul{
list-style:none;
}
ul li{
float:left;
line-height:40px;
text-align:center;
}
a{
text-decoration:none;
color:#000000;
display:block;
width:90px;
height:40px;
}
a:hover{
background-color:#666666;
color:#FFFFFF;
}
ul li ul li{
float:none;
background-color:#EEEEEE;
}
ul li ul{
display:none;
}
/*为了兼容IE7设置的CSS样式，但是又必须写在a:hover前面*/
ul li ul li a:link,ul li ul li a:visited{
background-color:#EEEEEE;
}
ul li ul li a:hover{
background-color:#009933;
}
</span>External JS script script.js file code:
<span style="font-size:18px;">function showsub(li){
var submenu=li.getElementsByTagName("ul")[0];
submenu.style.display="block";
}
function hidesub(li){
var submenu=li.getElementsByTagName("ul")[0];
submenu.style.display="none";
}</span> The above is the entire content of this article. I hope it will be helpful to everyone’s study and achieve the drop-down menu effect.
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