网站加载动画/预加载loading动画，再载入内容

默认情况下如果网站请求速度慢，所以会有一段时间的空白页面等等，用户体验效果不好，见到很多的页面都有预加载的效果，加载之前先加载一个动画，后台进程继续加载页面内容，当页面内容加载完之后再退出动画显示内容，这样的用户体验更好。

例如此链接：http://crusader12.com/C12HoverAlls/

这篇文章是从上面链接的内容上拔下来的，操作流程很简单，只有两部如下

首先定义一个loader.css文件，如下内容

.chromeframe {
    margin: 0.2em 0;
    background: #ccc;
    color: #000;
    padding: 0.2em 0;}
#loader-wrapper {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index:999999;}
#loader {
    display: block;
    position: relative;
    left: 50%;
    top: 50%;
    width: 150px;
    height: 150px;
    margin: -75px 0 0 -75px;
    border-radius: 50%;
    border: 3px solid transparent;
    /* COLOR 1 */
    border-top-color: #FFF;
    -webkit-animation: spin 2s linear infinite; /* Chrome, Opera 15+, Safari 5+ */
    -ms-animation: spin 2s linear infinite; /* Chrome, Opera 15+, Safari 5+ */
    -moz-animation: spin 2s linear infinite; /* Chrome, Opera 15+, Safari 5+ */ 
    -o-animation: spin 2s linear infinite; /* Chrome, Opera 15+, Safari 5+ */   
        animation: spin 2s linear infinite; /* Chrome, Firefox 16+, IE 10+, Opera */
    z-index:1001;}
#loader:before {
        content: "";
        position: absolute;
        top: 5px;
        left: 5px;
        right: 5px;
        bottom: 5px;
        border-radius: 50%;
        border: 3px solid transparent;
        /* COLOR 2 */       
        border-top-color: #FFF;
        -webkit-animation: spin 3s linear infinite; /* Chrome, Opera 15+, Safari 5+ */
        -moz-animation: spin 3s linear infinite; /* Chrome, Opera 15+, Safari 5+ */
        -o-animation: spin 3s linear infinite; /* Chrome, Opera 15+, Safari 5+ */
        -ms-animation: spin 3s linear infinite; /* Chrome, Opera 15+, Safari 5+ */              
        animation: spin 3s linear infinite; /* Chrome, Firefox 16+, IE 10+, Opera */}
#loader:after {
        content: "";
        position: absolute;
        top: 15px;
        left: 15px;
        right: 15px;
        bottom: 15px;
        border-radius: 50%;
        border: 3px solid transparent;
        border-top-color: #FFF;
        /* COLOR 3 */       
        -moz-animation: spin 1.5s linear infinite; /* Chrome, Opera 15+, Safari 5+ */
        -o-animation: spin 1.5s linear infinite; /* Chrome, Opera 15+, Safari 5+ */
        -ms-animation: spin 1.5s linear infinite; /* Chrome, Opera 15+, Safari 5+ */        
        -webkit-animation: spin 1.5s linear infinite; /* Chrome, Opera 15+, Safari 5+ */
          animation: spin 1.5s linear infinite; /* Chrome, Firefox 16+, IE 10+, Opera */}


@-webkit-keyframes spin {
        0%{ 
            -webkit-transform: rotate(0deg);  /* Chrome, Opera 15+, Safari 3.1+ */
            -ms-transform: rotate(0deg);  /* IE 9 */
            transform: rotate(0deg);  /* Firefox 16+, IE 10+, Opera */
        }100%{
            -webkit-transform: rotate(360deg);  /* Chrome, Opera 15+, Safari 3.1+ */
            -ms-transform: rotate(360deg);  /* IE 9 */
            transform: rotate(360deg);  /* Firefox 16+, IE 10+, Opera */}
}

@keyframes spin {
        0%{ 
            -webkit-transform: rotate(0deg);  /* Chrome, Opera 15+, Safari 3.1+ */
            -ms-transform: rotate(0deg);  /* IE 9 */
            transform: rotate(0deg);  /* Firefox 16+, IE 10+, Opera */
        }100%{
            -webkit-transform: rotate(360deg);  /* Chrome, Opera 15+, Safari 3.1+ */
            -ms-transform: rotate(360deg);  /* IE 9 */
            transform: rotate(360deg);  /* Firefox 16+, IE 10+, Opera */}
}


#loader-wrapper .loader-section {
        position: fixed;
        top: 0;
        width: 51%;
        height: 100%;
        background: #1abc9c; /* Old browsers */
        z-index: 1000;
        -webkit-transform: translateX(0);  /* Chrome, Opera 15+, Safari 3.1+ */
        -ms-transform: translateX(0);  /* IE 9 */
        transform: translateX(0);  /* Firefox 16+, IE 10+, Opera */}
#loader-wrapper .loader-section.section-left {left: 0;}
#loader-wrapper .loader-section.section-right {right: 0;}

/* Loaded */
.loaded #loader-wrapper .loader-section.section-left {
        -webkit-transform: translateX(-100%);  /* Chrome, Opera 15+, Safari 3.1+ */
            -ms-transform: translateX(-100%);  /* IE 9 */
                transform: translateX(-100%);  /* Firefox 16+, IE 10+, Opera */
        -webkit-transition: all 0.7s 0.3s cubic-bezier(0.645, 0.045, 0.355, 1.000);  
                transition: all 0.7s 0.3s cubic-bezier(0.645, 0.045, 0.355, 1.000);}
.loaded #loader-wrapper .loader-section.section-right {
        -webkit-transform: translateX(100%);  /* Chrome, Opera 15+, Safari 3.1+ */
            -ms-transform: translateX(100%);  /* IE 9 */
                transform: translateX(100%);  /* Firefox 16+, IE 10+, Opera */
        -webkit-transition: all 0.7s 0.3s cubic-bezier(0.645, 0.045, 0.355, 1.000);  
        transition: all 0.7s 0.3s cubic-bezier(0.645, 0.045, 0.355, 1.000);}
.loaded #loader {
        opacity: 0;
        -webkit-transition: all 0.3s ease-out;  
                transition: all 0.3s ease-out;}
.loaded #loader-wrapper {
        visibility: hidden;
        -webkit-transform: translateY(-100%);  /* Chrome, Opera 15+, Safari 3.1+ */
            -ms-transform: translateY(-100%);  /* IE 9 */
                transform: translateY(-100%);  /* Firefox 16+, IE 10+, Opera */
        -webkit-transition: all 0.3s 1s ease-out;  
                transition: all 0.3s 1s ease-out;}
/* JavaScript Turned Off */
.no-js #loader-wrapper {display: none;}
.no-js h1 {color: #222222;}
#loader-wrapper .load_title {
    font-family:'Open Sans';
    color:#FFF; font-size:19px; width:100%; text-align:center; z-index:9999999999999; position:absolute; top:60%; opacity:1; line-height:30px; }
#loader-wrapper .load_title span {  font-weight:normal; font-style:italic; font-size:13px; color:#FFF; opacity:0.5;}

第二步：在网站页面header标签和body标签加入以下代码

// 引入jquery 

<!--页面加载start-->
<link rel="stylesheet" type="text/css" href="css/loader.min.css">

<script type="text/javascript">         
    // 等待所有加载
    $(window).load(function(){
        $('body').addClass('loaded');
        $('#loader-wrapper .load_title').remove();
    }); 
</script>    

<div id="loader-wrapper">
    <div id="loader"></div>
    <div class="loader-section section-left"></div>
    <div class="loader-section section-right"></div>
    <div class="load_title">正在加载LoveFeel站点<br><span>V1.0</span></div>
</div>
<!--页面加载end-->