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透明渐变导航是一种解决滚动条通顶的变通方案。这篇文章主要介绍了原生JS实现 MUI导航栏透明渐变效果,需要的朋友可以参考下
mui内置有H5版本的透明渐变导航控件，教程参考mui官网；透明渐变导航是一种解决滚动条通顶的变通方案，相比双webview，具有更高的性能和更好的动画效果；
下面通过本文给大家分享基于原生JS实现 MUI导航栏透明渐变效果，具体内容详情如下所示：
首先声明：由于backgroundColor的值采用的是RGBA，IE8及以下不支持，所以此效果不支持IE8及以下的浏览器
css代码
body,p,h1{margin: 0;}
.module-layer{
width: 100%;
position: fixed;
top: 0;
left: 0;
z-index: 100000;
}
.module-layer-content{
position: relative;
min-width: 320px;
max-width: 750px;
width: 100%;
margin: 0 auto;
background-color: rgba(255, 0, 0, 0.9);
}
.module-layer-bg{
width: 100%;
height: 100%;
background: #000;
opacity: .7;
position: absolute;
top: 0;
left: 0;
z-index: -1;
}
.layer-head-name{
height: 50px;
line-height: 50px;
text-align: center;
padding: 0 50px;
font-size: 20px;
}
.layer-return,.layer-share{
width: 50px;
height: 50px;
line-height: 50px;
text-align: center;
position: absolute;
top:0;
z-index: 1;
}
.layer-return{left: 0;}
.layer-share{right: 0;}
.fixed-layer{
height: 100%;
display: none;
z-index: 100001;
}
.relative-layer{height: 100%;}
.layer-content{
padding:3%;
position: relative;
top: 20%;
}
.layer-close{
width: 2rem;
height: 2rem;
position: absolute;
top:3%;
right: 3%;
}
.pr {
position:relative;
}
#shop-input::-webkit-input-placeholder {
color:#fff;
}
#shop-input:-moz-placeholder {
color:#fff;
}
#shop-input::-moz-placeholder {
color:#fff;
}
#shop-input:-ms-input-placeholder {
color:#fff;
}
#shop-input {
border:none;
outline:none;
background:transparent;
}
.search-box {
height:30px;
border-radius:20px;
top:10px;
overflow:hidden;
z-index:10;
}
.search-box:after {
content:'';
display:block;
width:100%;
height:30px;
background:#fff;
opacity:.5;
position:absolute;
top:0;
left:0px;
z-index:-1;
}
#shop-input {
height:28px;
line-height:28px;
font-size:16px;
position:absolute;
top:0;
left:30px;
}
.shop-search {
width:16px;
height:16px;
position:absolute;
top:7px;
left:6px;
}
.layer-return{
background: url(images/return.png) no-repeat center center/12px 20px;
}
.layer-share{
background: url(images/share.png) no-repeat center center/20px 30px;
}
a {
-webkit-tap-highlight-color: transparent;
-webkit-touch-callout: none;
-webkit-user-select: none;
}
.module-content{
min-width: 320px;
max-width: 750px;
width: 100%;
margin: 0 auto;
background: #fff;
}
.module-content div:first-child img{margin-top: 0;}
.module-content div img{
display: block;
width: 100%;
margin-top: 10px;
}
HTML代码
<header class="module-layer">
<div class="module-layer-content">
<p class="layer-return"></p>
<h1 class="layer-head-name">
<div class="pr search-box">
<img class="shop-search" src="images/search.png"/>
<input id="shop-input" type="text" placeholder="搜索店内商品" value="" />
</div>
</h1>
<p class="layer-share"></p>
</div>
</header>
<div class="module-content">
<div><img src="images/banner.png"/></div>
<div><img src="images/banner1.png"/></div>
<div><img src="images/banner3.png"/></div>
<div><img src="images/banner4.jpg"/></div>
<div><img src="images/banner5.png"/></div>
<div><img src="images/banner6.png"/></div>
<div><img src="images/banner7.jpg"/></div>
<div><img src="images/banner8.jpg"/></div>
</div>
JS代码
(function(){
//获取滚动条当前位置
function getScrollTop(){
var scrollTop = 0, bodyScrollTop = 0, documentScrollTop = 0;
if(document.body){
bodyScrollTop = document.body.scrollTop;
}
if(document.documentElement){
documentScrollTop = document.documentElement.scrollTop;
}
scrollTop = (bodyScrollTop - documentScrollTop > 0) ? bodyScrollTop : documentScrollTop;
return scrollTop;
}
//获取CSS样式
function getStyle(element, attr){
if(element.currentStyle){
return element.currentStyle[attr];
}else{
return window.getComputedStyle(element,null)[attr];
}
}
//获取原始backgroundColor值
var color = getStyle(document.getElementsByClassName('module-layer-content')[0],'backgroundColor');
//取到RGB
var colorRgb = color.substring(0,color.lastIndexOf(',') + 1);
//取到A
var colorA = color.substring(color.lastIndexOf(',') + 1,color.length - 1);
//对A判断，如果最终值小于0.9，直接设置为1
if(colorA < 0.9){colorA = 1;}
//设置背景色的A的函数
var setCoverOpacity = function() {
document.getElementsByClassName('module-layer-content')[0].style.background = colorRgb + (((getScrollTop() / 550) > colorA) ? colorA : (getScrollTop() / 550)) + ')';
}
//初始化函数
setCoverOpacity();
//绑定滚动监听事件
window.addEventListener('scroll',setCoverOpacity,false);
}())
注意：
不兼容IE8及以下的IE浏览器；
550是滚动条到达位置的最终透明度，此处根据需要自定义；
CSS终背景颜色的RGBA的A是最终透明度
总结
以上所述是小编给大家介绍的原生JS实现 MUI导航栏透明渐变效果，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持！ | 
发表于 2017-11-7 11:48:58
