一 、css实现
html代码部分
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>html+css下拉菜单</title> <link type="text/css" href="https://www.jb51.net/css/style.css" /> </head> <body> <ul> <li> <a href="#" >首页</a> </li> <li> <a href="#" >菜单一</a> <ul> <li>内容一</li> <li>内容一</li> <li>内容一</li> </ul> </li> <li> <a href="#" >菜单二</a> <ul> <li>内容二</li> <li>内容二</li> <li>内容二</li> </ul> </li> <li> <a href="#" >菜单三</a> <ul> <li>内容三</li> <li>内容三</li> <li>内容三</li> </ul> </li> <li> <a href="#" >菜单四</a> </li> </ul> </body> </html>
css部分
*{ padding: 0; margin: 0; } a{ text-decoration: none; color: #000; } ul,li{ list-style: none; } .menu{ margin: 50px auto; width: 500px; height: 35px; background-color: #ccc; text-align: center; line-height: 35px; } .menu li{ float: left; width: 20%; position: relative; } .menu li:hover ul{ display: block; } .menu li a{ display: block; } .menu li a:hover{ background-color: burlywood; } .menu li ul{ display: none; position: absolute; } .menu li ul li{ width: 100%; margin-top: 2px; background-color: darkgray; } .menu li ul li:hover{ cursor: pointer; background-color: chartreuse; }
二、js实现
html和js部分（实现方法一）
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>JS下拉菜单</title> <link type="text/css" href="https://www.jb51.net/css/style.css" /> </head> <body> <ul> <li> <a href="#" >首页</a> </li> <li> <a href="#" >菜单一</a> <ul> <li>内容一</li> <li>内容一</li> <li>内容一</li> </ul> </li> <li> <a href="#" >菜单二</a> <ul> <li>内容二</li> <li>内容二</li> <li>内容二</li> </ul> </li> <li> <a href="#" >菜单三</a> <ul> <li>内容三</li> <li>内容三</li> <li>内容三</li> </ul> </li> <li> <a href="#" >菜单四</a> </li> </ul> <script type="text/javascript"> window.onload = function(){ function $(id){ return typeof id == "string"?document.getElementById(id):id; } var menu_li = $("menu").getElementsByTagName("li"); for(var i = 0; i < menu_li.length; i++){ menu_li[i].onmouseover = function(){ var ss = this.getElementsByTagName("ul")[0]; if(ss != undefined){ ss.style.display = "block"; } } } for(var j = 0; j < menu_li.length; j++){ menu_li[j].onmouseout = function(){ var ssa = this.getElementsByTagName("ul")[0]; if(ssa != undefined){ ssa.style.display = "none"; } } } } </script> </body> </html>
html和js部分（实现方法二）
<!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <style> * { padding: 0; margin: 0; } li { list-style: none; float: left; } #tabCon { clear: both; } #tabCon div { display: none; } #tabCon div.fdiv { display: block; } </style> </head> <body> <div> <div> <ul> <li>标题一</li> <li>标题二</li> <li>标题三</li> <li>标题四</li> </ul> </div> <div> <div>内容一</div> <div>内容二</div> <div>内容三</div> <div>内容四</div> </div> </div> </body> <script> function $(id){ return typeof id=="string"?document.getElementById(id):id; } var EventUtil = { addHandler: function(element, type, handler) { if(element.addEventListener) { element.addEventListener(type, handler, false); } else if(element.attachEvent) { element.attachEvent("on" + type + handler); } else { element["on" + type] = handler; } }, removeHandler: function(element, type, handler) { if(element.removeEventListener) { element.removeEventListener(type, handler, false); } else if(element.detachEvent) { element.detachEvent("on" + type + handler); } else { element["on" + type] = null; } } } var tabs = $("tab").getElementsByTagName("li"); var divs = $("tabCon").getElementsByTagName("div"); for(var i = 0; i < tabs.length; i++) { var set = function() { change(this); } EventUtil.addHandler(tabs[i], "click", set); //tabs[i].onclick=function(){change(this);} } function change(obj) { console.log(obj); for(var i = 0; i < tabs.length; i++) { if(tabs[i] == obj) {console.log(tabs[i]); // tabs[i].style.display = "block"; divs[i].style.display = "block"; } else { // tabs[i].style.display = "none"; divs[i].style.display = "none"; } } } </script> </html>
css部分