实现如图所示的动画效果：
预载动画一：双旋圈
在两个不同方向旋转的圆圈。我们对内圈的转速定义了一个CSS代码，即内圈比外圈的速率快2倍。
实现如图所示：
html代码：
<body style="background: #ffb83c;"> <p id="preloader-1"> <span></span> <span></span> </p> </body>
css代码：
#preloader-1{
position: relative;
}
#preloader-1 span{
position: absolute;
border:8px solid #fff;
border-top:8px solid transparent;
border-radius: 999px;
}
#preloader-1 span:nth-child(1){
width:80px;
height: 80px;
animation: spin-1 2s infinite linear;
}
#preloader-1 span:nth-child(2){
top:20px;
left:20px;
width:40px;
height: 40px;
animation: spin-2 1s infinite linear;
}
@keyframes spin-1{
0%{transform: rotate(360deg); opacity: 1.0;}
50%{transform: rotate(180deg); opacity: 0.5;}
100%{transform: rotate(0deg);opacity: 0;}
}
@keyframes spin-2{
0%{transform: rotate(0deg); opacity: 0.5;}
50%{transform: rotate(180deg); opacity: 1;}
100%{transform: rotate(360deg);opacity: 0.5;}
}预载动画二：交错圈
两个圆圈进行横向交错来回移动。每个圆圈都设置了单独的反向移动动画参数。
效果：
html代码：
<body style="background: #4ad3b4;"> <p id="preloader-2"> <span></span> <span></span> </p> </body>
css代码：
#preloader-2{
position: relative;
}
#preloader-2 span{
position: absolute;
width:30px;
height: 30px;
background: #fff;
border-radius: 999px;
}
#preloader-2 span:nth-child(1){
animation: cross-1 1.5s infinite linear;
}
#preloader-2 span:nth-child(2){
animation: cross-2 1.5s infinite linear;
}
@keyframes cross-1{
0%{transform: translateX(0); opacity: 0.5;}
50%{transform: translateX(80px); opacity: 1;}
100%{transform: translateX(0);opacity: 0.5;}
}
@keyframes cross-2{
0%{transform: translateX(80px); opacity: 0.5;}
50%{transform: translateX(0); opacity: 1;}
100%{transform: translateX(80px);opacity: 0.5;}
}预载动画三：旋转圈
效果：
html代码：
<body style="background: #ab69d9;"> <p id="preloader-3"> <span></span> </p> </body>
css代码：
#preloader-3{
position: relative;
width:80px;
height: 80px;
border:4px solid rgba(255,255,255,.25);
border-radius: 999px;
}
#preloader-3 span{
position: absolute;
width:80px;
height:80px;
border:4px solid transparent;
border-top:4px solid #fff;
border-radius: 999px;
top:-4px;
left:-4px;
animation: rotate 1s infinite linear;
}
@keyframes rotate{
0%{transform: rotate(0deg);}
100%{transform: rotate(360deg);}
}预载动画四：跳动圈
这是一种墨西哥波浪纹的动画效果，通过设置不同圆圈之间的延迟参数来实现。
效果：
html代码：
<body style="background: #c1da;"> <p id="preloader-4"> <span></span> <span></span> <span></span> <span></span> <span></span> </p> </body>
css代码：
#preloader-4{
position: relative;
}
#preloader-4 span{
position:absolute;
width:16px;
height: 16px;
border-radius: 999px;
background: #fff;
animation: bounce 1s infinite linear;
}
#preloader-4 span:nth-child(1){
left:0;
animation-delay: 0s;
}
#preloader-4 span:nth-child(2){
left:20px;
animation-delay: 0.25s;
}
#preloader-4 span:nth-child(3){
left:40px;
animation-delay: 0.5s;
}
#preloader-4 span:nth-child(4){
left:60px;
animation-delay: 0.75s;
}
#preloader-4 span:nth-child(5){
left:80px;
animation-delay: 1.0s;
}
@keyframes bounce{
0%{transform: translateY(0px);opacity: 0.5;}
50%{transform: translateY(-30px);opacity: 1.0;}
100%{transform: translateY(0px);opacity: 0.5;}
}预载动画五：雷达圈
一种雷达辐射效果，给3个span elements设置相同的淡入淡出效果，再予每个稍微延迟下即可实现。
效果：
html代码：
<body style="background: #f9553f;"> <p id="preloader-5"> <span></span> <span></span> <span></span> </p> </body>
css代码：
#preloader-5{
position: relative;
}
#preloader-5 span{
position:absolute;
width:50px;
height: 50px;
border:5px solid #fff;
border-radius: 999px;
opacity: 0;
animation: radar 2s infinite linear;
}
#preloader-5 span:nth-child(1){
animation-delay: 0s;
}
#preloader-5 span:nth-child(2){
animation-delay: 0.66s;
}
#preloader-5 span:nth-child(3){
animation-delay: 1.33s;
}
@keyframes radar{
0%{transform: scale(0);opacity: 0;}
25%{transform: scale(0);opacity: 0.5;}
50%{transform: scale(1);opacity: 1.0;}
75%{transform: scale(1.5);opacity: 0.5;}
100%{transform: scale(2);opacity: 0;}
}下载本文