近处的大树枝叶茂盛。小草叶子又肥又美。小花绚丽多姿。一阵阵风吹来，花草树木，一起奏出了森林交响曲，一只只蝴蝶随着交响曲跳起了舞呢。
实现效果
html
<div class="container">
<h1 class="title">Dropdown Menu</h1>
<ul>
<li class="dropdown">
<a rel="nofollow noopener noreferrer" href="#" data-toggle="dropdown">First Menu <i class="icon-arrow"></i></a>
<ul class="dropdown-menu">
<li><a rel="nofollow noopener noreferrer" href="#">Home</a></li>
<li><a rel="nofollow noopener noreferrer" href="#">About Us</a></li>
<li><a rel="nofollow noopener noreferrer" href="#">Services</a></li>
<li><a rel="nofollow noopener noreferrer" href="#">Contact</a></li>
</ul>
</li>
<li class="dropdown">
<a rel="nofollow noopener noreferrer" href="#" data-toggle="dropdown">Second Menu <i class="icon-arrow"></i></a>
<ul class="dropdown-menu">
<li><a rel="nofollow noopener noreferrer" href="#">Home</a></li>
<li><a rel="nofollow noopener noreferrer" href="#">About Us</a></li>
<li><a rel="nofollow noopener noreferrer" href="#">Services</a></li>
<li><a rel="nofollow noopener noreferrer" href="#">Contact</a></li>
</ul>
</li>
<li class="dropdown">
<a rel="nofollow noopener noreferrer" href="#" data-toggle="dropdown">Third Menu <i class="icon-arrow"></i></a>
<ul class="dropdown-menu">
<li><a rel="nofollow noopener noreferrer" href="#">Home</a></li>
<li><a rel="nofollow noopener noreferrer" href="#">About Us</a></li>
<li><a rel="nofollow noopener noreferrer" href="#">Services</a></li>
<li><a rel="nofollow noopener noreferrer" href="#">Contact</a></li>
</ul>
</li>
</ul>
<p class="text-center">
See this same menu only with CSS3: <a rel="nofollow noopener noreferrer" href="https://codepen.io/pedronauck/pen/jaluz" target="_blank">https://codepen.io/pedronauck/pen/jaluz</a>
</p>
</div>
css
@import "compass/css3";
@import url("https://fonts.googleapis.com/css?family=Lato:300,400,700,900");
@import url(https://fonts.googleapis.com/css?family=Pacifico);
body {
font-family: "Lato", Helvetica, Arial;
font-size: 16px;
}
.text-center {
text-align: center;
}
*, *:before, *:after {
-webkit-border-sizing: border-box;
-moz-border-sizing: border-box;
border-sizing: border-box;
}
.container {
width: 350px;
margin: 50px auto;
& > ul {
list-style: none;
padding: 0;
margin: 0 0 20px 0;
}
}
// =============================================================================
// Mixins and Variables
// =============================================================================
$blue: #2980B9;
$gray: #EEE;
@mixin ul-nostyle {
list-style: none;
padding: 0;
margin: 0;
}
@mixin double-shadow($color) {
@include box-shadow(0 1px 0 lighten($color, 10%) inset, 0 -1px 0 darken($color, 10%) inset);
}
@mixin hover-style($color) {
&:hover {
background: lighten($color, 3%);
}
}
@mixin animation($content) {
animation: $content;
-moz-animation: $content;
-webkit-animation: $content;
}
@mixin keyframes($name) {
@keyframes #{$name} { @content; }
@-moz-keyframes #{$name} { @content; }
@-webkit-keyframes #{$name} { @content; }
}
// =============================================================================
// Classes
// =============================================================================
.title {
font-family: 'Pacifico';
font-weight: norma;
font-size: 40px;
text-align: center;
line-height: 1.4;
color: $blue;
}
.dropdown {
a {
text-decoration: none;
}
[data-toggle="dropdown"] {
position: relative;
display: block;
color: white;
background: $blue;
@include double-shadow($blue);
@include hover-style($blue);
@include text-shadow(0 -1px 0 rgba(0,0,0,0.3));
padding: 10px;
}
.icon-arrow {
position: absolute;
display: block;
font-size: 0.7em;
color: #fff;
top: 14px;
right: 10px;
&.open {
@include transform(rotate(-180deg));
@include transition(transform .6s);
}
&.close {
@include transform(rotate(0deg));
@include transition(transform .6s);
}
&:before {
content: '\25BC';
}
}
.dropdown-menu {
max-height: 0;
overflow: hidden;
@include ul-nostyle;
li {
padding: 0;
a {
display: block;
color: darken($gray, 50%);
background: $gray;
@include double-shadow($gray);
@include hover-style($gray);
@include text-shadow(0 -1px 0 rgba(255,255,255,0.3));
padding: 10px 10px;
}
}
}
.show, .hide {
@include transform-origin(50%, 0%);
}
.show {
display: block;
max-height: 9999px;
@include transform(scaleY(1));
@include animation(showAnimation .5s ease-in-out);
@include transition(max-height 1s ease-in-out);
}
.hide {
max-height: 0;
@include transform(scaleY(0));
@include animation(hideAnimation .4s ease-out);
@include transition(max-height .6s ease-out);
}
}
@include keyframes(showAnimation) {
0% {
@include transform(scaleY(0.1));
}
40% {
@include transform(scaleY(1.04));
}
60% {
@include transform(scaleY(0.98));
}
80% {
@include transform(scaleY(1.04));
}
100% {
@include transform(scaleY(0.98));
}
80% {
@include transform(scaleY(1.02));
}
100% {
@include transform(scaleY(1));
}
}
@include keyframes(hideAnimation) {
0% {
@include transform(scaleY(1));
}
60% {
@include transform(scaleY(0.98));
}
80% {
@include transform(scaleY(1.02));
}
100% {
@include transform(scaleY(0));
}
}
js
// Dropdown Menu
var dropdown = document.querySelectorAll('.dropdown');
var dropdownArray = Array.prototype.slice.call(dropdown,0);
dropdownArray.forEach(function(el){
var button = el.querySelector('a[data-toggle="dropdown"]'),
menu = el.querySelector('.dropdown-menu'),
arrow = button.querySelector('i.icon-arrow');
button.onclick = function(event) {
if(!menu.hasClass('show')) {
menu.classList.add('show');
menu.classList.remove('hide');
arrow.classList.add('open');
arrow.classList.remove('close');
event.preventDefault();
}
else {
menu.classList.remove('show');
menu.classList.add('hide');
arrow.classList.remove('open');
arrow.classList.add('close');
event.preventDefault();
}
};
})
Element.prototype.hasClass = function(className) {
return this.className && new RegExp("(^|\\s)" + className + "(\\s|$)").test(this.className);
};
以上就是HTML+CSS3+JS 实现的下拉菜单的详细内容，更多关于HTML+CSS3+JS 下拉菜单的资料请关注其它相关文章！
