试例：
6f79b1e7-f7b2-437b-9add-e817ab2e3cf8.gif
loading的js引入文件必须放<head>内
html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width,initial-scale=1,minimum-scale=1,maximum-scale=1,user-scalable=no">
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="black">
<meta name="format-detection" content="telephone=no">
<meta name="keywords" content="" />
<title>loading</title>
<script src="js/base_loading.js" type="text/javascript" charset="utf-8"></script>
</head>
<style>
@keyframes loading_save {
from { transform: rotate(0deg); }
to { transform: rotate(360deg); }
}
*{
margin: 0;
padding: 0;
}
ul{
width: 100%;
}
li{
width: 100%;
text-align: center;
list-style: none;
}
ul img{
width: 100%;
}
</style>
<body>
<ul >
//这里的图尽量使用大图 方便测试效果 我这里的图一张就有接近2M
<li><img src="img/1.png" ></li>
<li><img src="img/2.png" ></li>
<li><img src="img/3.png" ></li>
<li><img src="img/4.png" ></li>
<li><img src="img/5.png" ></li>
<li>哈哈哈哈</li>
<li>哈哈哈哈</li>
<li>哈哈哈哈</li>
<li>哈哈哈哈</li>
<li>哈哈哈哈</li>
<li>哈哈哈哈</li>
<li>哈哈哈哈</li>
<li>哈哈哈哈</li>
<li>哈哈哈哈</li>
<li>哈哈哈哈</li>
<li>哈哈哈哈</li>
<li>哈哈哈哈</li>
</ul>
</body>
</html>
base_loading.js
//获取浏览器页面可见高度和宽度
var _PageHeight = document.documentElement.clientHeight;
//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 > 61 ? (_PageHeight - 61) / 2 : 0;
var html=document.documentElement
html.setAttribute('style','overflowY:hidden;overflow:hidden;height:' + _PageHeight + 'px;')
//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="height: 100%;display: flex;justify-content: center;align-items: center;left: 0;top: 0;position:fixed;left:0;width:100%;height:' + _PageHeight + 'px;top:0;background:#efeff4;opacity:1;filter:alpha(opacity=80);z-index:10000;"><div id="box" style=" cursor1: wait; text-align: center; top:' + _LoadingTop + 'px; color: #696969; font-family:\'Microsoft YaHei\'; line-height: 1.5;border-radius: 5px; padding: 15px 15px; background-color: rgba(58, 58, 58, 0.9);"><div style=""><svg id="loading" style="width:35px; -webkit-animation: loading_save 1s linear infinite;animation: loading_save 1s linear infinite;" viewBox="0 -2 59.75 60.25" width="100%" height="100%"><path fill="#ccc" d="M29.69-.527C14.044-.527 1.36 12.158 1.36 27.806S14.043 56.14 29.69 56.14c15.65 0 28.334-12.686 28.334-28.334S45.34-.527 29.69-.527zm.185 53.75c-14.037 0-25.417-11.38-25.417-25.417S15.838 2.39 29.875 2.39s25.417 11.38 25.417 25.417-11.38 25.416-25.417 25.416z"></path><path fill="none" stroke="#108ee9" stroke-width="3" stroke-linecap="round" stroke-miterlimit="10" d="M56.587 29.766c.37-7.438-1.658-14.7-6.393-19.552"></path></svg></img></div><div style="font-size:15px; color:#fff">努力加载中...</div></div></div>';
//呈现loading效果
document.write(_LoadingHtml);
//window.onload = function () {
// var loadingMask = document.getElementById('loadingDiv');
// loadingMask.parentNode.removeChild(loadingMask);
//};
//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 == "interactive" ){//当页面状态为interactive 才能获取到body元素
//解决移动端还可以下滑页面 出现滚动条
document.body.setAttribute('style','overflowY:hidden;overflow:hidden;height:' + _PageHeight + 'px;')
}
if (document.readyState == "complete") {
var loadingMask = document.getElementById('loadingDiv');
document.body.setAttribute('style','overflowY:unset;overflow:unset;height:unset;')
html.setAttribute('style','overflowY:unset;overflow:unset;height:unset;')
loadingMask.parentNode.removeChild(loadingMask);
}
}
