html页面Loading效果

<link rel="stylesheet" href="loading.css">
<script src="loading.js"></script>

.spinner {
  width: 60px;
  height: 60px;
  background-image: linear-gradient(0deg,#8a76f6,#70cafe);
 
  margin: 100px auto;
  -webkit-animation: rotateplane 1.2s infinite ease-in-out;
  animation: rotateplane 1.2s infinite ease-in-out;
  
}
 
@-webkit-keyframes rotateplane {
  0% { -webkit-transform: perspective(120px) }
  50% { -webkit-transform: perspective(120px) rotateY(180deg) }
  100% { -webkit-transform: perspective(120px) rotateY(180deg)  rotateX(180deg) }
}
 
@keyframes rotateplane {
  0% {
    transform: perspective(120px) rotateX(0deg) rotateY(0deg);
    -webkit-transform: perspective(120px) rotateX(0deg) rotateY(0deg)
  } 50% {
    transform: perspective(120px) rotateX(-180.1deg) rotateY(0deg);
    -webkit-transform: perspective(120px) rotateX(-180.1deg) rotateY(0deg)
  } 100% {
    transform: perspective(120px) rotateX(-180deg) rotateY(-179.9deg);
    -webkit-transform: perspective(120px) rotateX(-180deg) rotateY(-179.9deg);
  }
}

//获取浏览器页面可见高度和宽度  
    var _PageHeight = document.documentElement.clientHeight,  
        _PageWidth = document.documentElement.clientWidth;  
    //计算loading框距离顶部和左部的距离（loading框的宽度为215px，高度为61px）  
    var _LoadingTop = _PageHeight > 90 ? (_PageHeight - 90) / 2 : 0,  
        _LoadingLeft = _PageWidth > 90 ? (_PageWidth - 90) / 2 : 0;  
    //在页面未加载完毕之前显示的loading Html自定义内容  
    var _LoadingHtml = '<div id="loadingDiv" style="position:absolute;left:0;width:100%;height:' + _PageHeight + 'px;top:0;background:#FFFFFF;opacity:1.0;filter:alpha(opacity=80);z-index:10000;"><div class="spinner" style="position: top: 60px; margin:' + _LoadingTop + 'px auto ;"></div></div>';  
    //呈现loading效果  
    document.write(_LoadingHtml);  
 
    //监听加载状态改变  
    document.onreadystatechange = completeLoading;  
    
    //加载状态为complete时移除loading效果  
function completeLoading() {  
  if (document.readyState == "complete") {  
  $("#loadingDiv").fadeOut(1500);
  }  
}