网页首页添加加载动画

来源：https://ihatetomatoes.net/create-custom-preloading-screen/

第一步：为加载页添加html及css代码

<div id="loader-wrapper">
    <div id="loader"></div>
    <div class="loader-section section-left"></div>
    <div class="loader-section section-right"></div>
</div>

#loader-wrapper { position: fixed; top: 0; left: 0; width: 100%; height: 100%; z-index: 2000; }
#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; border-top-color: #3498db; -webkit-animation: spin 2s linear infinite; /* Chrome, Opera 15+, Safari 5+ */
    animation: spin 2s linear infinite; /* Chrome, Firefox 16+, IE 10+, Opera */ z-index: 2001; }
#loader:before { content: ""; position: absolute; top: 5px; left: 5px; right: 5px; bottom: 5px; border-radius: 50%; border: 3px solid transparent;
    border-top-color: #e74c3c; -webkit-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: #f9c922; -webkit-animation: spin 1.5s linear infinite; /* Chrome, Opera 15+, Safari 5+ */ animation: spin 1.5s linear infinite; /* Chrome, Firefox 16+, IE 10+, Opera */ }
.large-header {
    position: fixed;top: 0px;
}
@-webkit-keyframes spin {
    0%   {
        -webkit-transform: rotate(0deg);  /* Chrome, Opera 15+, Safari 3.1+ */  /* IE 9 */
        transform: rotate(0deg);  /* Firefox 16+, IE 10+, Opera */
    }
    100% {
        -webkit-transform: rotate(360deg);  /* Chrome, Opera 15+, Safari 3.1+ */  /* IE 9 */
        transform: rotate(360deg);  /* Firefox 16+, IE 10+, Opera */
    }
}
@keyframes spin {
    0%   {
        -webkit-transform: rotate(0deg);  /* Chrome, Opera 15+, Safari 3.1+ */  /* IE 9 */
        transform: rotate(0deg);  /* Firefox 16+, IE 10+, Opera */
    }
    100% {
        -webkit-transform: rotate(360deg);  /* Chrome, Opera 15+, Safari 3.1+ */  /* IE 9 */
        transform: rotate(360deg);  /* Firefox 16+, IE 10+, Opera */
    }
}

#loader-wrapper .loader-section { position: fixed; top: 0; width: 51%; height: 100%; background: #222222; z-index: 2000; -webkit-transform: translateX(0);  /* Chrome, Opera 15+, Safari 3.1+ */  /* 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+ */  /* IE 9 */
    transform: translateX(-100%);  /* Firefox 16+, IE 10+, Opera */
    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+ */  /* IE 9 */
    transform: translateX(100%);  /* Firefox 16+, IE 10+, Opera */
    transition: all 0.7s 0.3s cubic-bezier(0.645, 0.045, 0.355, 1.000);
}

.loaded #loader {
    opacity: 0;
    transition: all 0.3s ease-out;
}
.loaded #loader-wrapper {
    visibility: hidden;

    -webkit-transform: translateY(-100%);  /* Chrome, Opera 15+, Safari 3.1+ */  /* IE 9 */
    transform: translateY(-100%);  /* Firefox 16+, IE 10+, Opera */
    transition: all 0.3s 1s ease-out;
}

/* JavaScript Turned Off */
.no-js #loader-wrapper {
    display: none;
}

.cd-hero-slider.small-screen { height: 100%; }
.cd-hero-slider .js-tm-page-content.tm-page-1 { margin-top: 70px; }

第二步，在加载完成的处理中添加一点js代码

$(window).load(function(){
    //添加以下代码
    $('body').addClass('loaded');
})