vue项目加载前空白的动画过渡效果

参考：https://github.com/mgbq/nx-admin

复制以下html内容到项目的index.html中即可：

  <style>
    html,
    body,
    #app {
      height: 100%;
      margin: 0px;
      padding: 0px;
    }
    .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: #7171C6;
      /* 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;
    }
  </style>

  <div id="app">
    <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 nx-admin,请耐心等待
        <br>
        <span>V1.3</span>
      </div>
    </div>
  </div>