//獲取瀏覽器頁面可見高度和寬度
var _PageHeight = document.documentElement.clientHeight,
_PageWidth = document.documentElement.clientWidth;
//計算loading框距離頂部和左部的距離（loading框的寬度為215px，高度為61px）
var _LoadingTop = _PageHeight > 61 ? (_PageHeight - 61) / 2 : 0,
_LoadingLeft = _PageWidth > 215 ? (_PageWidth - 215) / 2 : 0;
//加載gif地址
var Loadimagerul="/Content/LoadJs/Image/loading.gif";
//在頁面未加載完畢之前顯示的loading Html自定義內(nèi)容
var _LoadingHtml = '<div id="loadingDiv" style="position:absolute;left:0;width:100%;height:' + _PageHeight + 'px;top:0;background:#f3f8ff;opacity:1;filter:alpha(opacity=80);z-index:10000;"><div style="position: absolute; cursor1: wait; left: ' + _LoadingLeft + 'px; top:' + _LoadingTop + 'px; width:100px;; height: 57px; line-height: 57px; padding-left: 50px; padding-right: 5px; background: #fff url('+Loadimagerul+') no-repeat scroll 5px 12px; border: 2px solid #95B8E7; color: #696969; font-family:\'Microsoft YaHei\';">玩命加載中...</div></div>';
//呈現(xiàn)loading效果
document.write(_LoadingHtml);
//監(jiān)聽加載狀態(tài)改變
document.onreadystatechange = completeLoading;
//加載狀態(tài)為complete時移除loading效果
function completeLoading() {
if (document.readyState == "complete") {
var loadingMask = document.getElementById('loadingDiv');
loadingMask.parentNode.removeChild(loadingMask);
}
}

<script src="~/Content/LoadJs/base-loading.js"></script>