頁面loading效果

1、JS代碼：
	//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框的寬度爲215px，高度爲61px）
        var _LoadingTop = _PageHeight > 61 ? (_PageHeight - 61) / 2 : 0,
            _LoadingLeft = _PageWidth > 215 ? (_PageWidth - 215) / 2 : 0;
        //在頁面未加載完畢以前顯示的loading Html自定義內容
        var _LoadingHtml = '<div id="loadingDiv" style="position:absolute;left:0;width:100%;height:' + _PageHeight + 'px;top:0;background:#f3f8ff;opacity:0.8;filter:alpha(opacity=80);z-index:10000;"><div style="position: absolute; cursor1: wait; left: ' + _LoadingLeft + 'px; top:' + _LoadingTop + 'px; width: auto; height: 57px; line-height: 57px; padding-left: 50px; padding-right: 5px; background: #fff url(/Content/loading.gif) no-repeat scroll 5px 10px; border: 2px solid #95B8E7; color: #696969; font-family:\'Microsoft YaHei\';">頁面加載中，請等待...</div></div>';
        //呈現loading效果
        document.write(_LoadingHtml);
 
        //window.onload = function () {
        //    var loadingMask = document.getElementById('loadingDiv');
        //    loadingMask.parentNode.removeChild(loadingMask);
        //};
 
        //監聽加載狀態改變
        document.onreadystatechange = completeLoading;
 
        //加載狀態爲complete時移除loading效果
        function completeLoading() {
            if (document.readyState == "complete") {
                var loadingMask = document.getElementById('loadingDiv');
                loadingMask.parentNode.removeChild(loadingMask);
            }
        }