目录
- 鼠标经过展开下拉菜单
- 方法一
- 方法二
<!DOCTYPE html><html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>js实现下拉二级菜单</title> <style> * { margin: 0px; padding: 0px; } body { font-family: Verdana, Geneva, sans-serif; font-size: 14px; } #nav { width: 600px; height: 40px; background-color: #eee; margin: 0 auto; } ul { list-style: none; } ul li { float: left; line-height: 40px; text-align: center; width: 100px; /*ie7显示宽度的兼容性 设置width 而不用padding的自适应 */ } a { text-decoration: none; color: #000; display: block; } a:hover { color: #f00; background-color: #666; } ul li ul li { float: none; background-color: #eee; margin: 2px 0px; } ul li ul { display: none; } </style> </head> <body> <div id="nav"> <ul> <li><a href="#">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="#">Html/CSS</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="#">实例练习</a></li> <li><a href="#">问与答</a></li> </ul> </li> <li><a href="#">经典案例</a></li> <li><a href="#">关于我们</a></li> </ul> </div> <script> function ShowSub(li) { //函数定义 var subMenu = li.getEleme��û��,�����ûntsByTagName("ul")[0]; //获取 subMenu.style.display = " block "; } function HideSub(li) { var subMenu = li.getElementsByTagName("ul")[0]; subMenu.style.display = " none "; } </script> </body></html>方法二<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <style type="text/css"> * { margin: 0px; } a{ text-decoration: none; font-size: 16px; color: #333; } #nav { width: 700px; height: 40px; background: #ddd; margin: 20px auto; } #nav ul { list-style: none; } #nav ul li { width: 120px; float: left; } #nav ul li a { display: block; text-align: center; line-height: 40px; } #nav ul li a:hover { background: #CCCCDD; } #nav ul li div { font-size: 18px; display: none; } #nav ul li div a { line-height: 40px; text-align: center; background: #ddd; } #nav ul li div a:hover { background: #FF9090; } </style></head><body> <div id="nav"> <ul> <li> <a href="#">首页</a> </li> <li> <a href="#">课程大厅</a> <div> <a href="#">JavaScript</a> <a href="#">html/css</a> <a href="#">Bootstrap</a> </div> </li> <li> <a href="">学习中心</a> <div> <a href="#">视频中心</a> <a href="#">实例练习</a> <a href="#">问与答</a> </div> </li> <li><a href="#">经典案例</a></li> <li><a href="#">关于我们</a></li> </ul> </div> <script type="text/javascript"> window.onload = function () { var aLi = document.getElementById("nav").getElementsByTagName("li"); for (var i = 0; i < aLi.length; i++) { aLi[i].onmouseover = function () { if( this.children[1]){ this.children[1].style.display = 'block';//选取当前li元素的第二个子元素 } } aLi[i].onmouseout = function () { if( this.children[1]){ this.children[1].style.display = 'none'; } } } } </script></body></html>