javascript window loading mask embedded web content_javascript skills

Copy code The code is as follows:

//Initialize navigation background, iframe container
function fnDaoHangBg()
{
var h = fnGetHeight(),w = fnGetWidth();//Get the background window size
if(!$('divDaoHangBg'))
{
var div = $ C('div');//Create a background mask
div.id = 'divDaoHangBg';
div.style.backgroundColor = 'black';
div.style.position = 'absolute';
div.style.filter = 'alpha(opacity=80)';
div.style.opacity = '.80';
div.style.zIndex = 100001;
div.style. left = 0;
div.style.top = 0;
div.style.width = w 'px';
div.style.height= h 'px';
document.body. appendChild(div);
}

if(!$('divDaoHangBgIframe'))
{
var iframe;
iframe = this.$C('IFRAME'); //Create an inline iframe container within the mask for embedded display of other web pages
iframe.id = 'divDaoHangBgIframe';
iframe.frameBorder = '0';
iframe.scrolling = "no" ;
iframe.style.overflow = 'hidden';
iframe.allowTransparency = 'true';
iframe.style.display = 'none';
iframe.style.width = w 'px ';//800
iframe.style.height = h 'px';//620
iframe.style.marginTop = '75px';//800
$('divDaoHangBg').appendChild( iframe);
}
if(!$('divDaoHangBgClose'))
{
var div = $C('div');//Create a close button on the mask
div.id = 'divDaoHangBgClose';
div.style.position = 'absolute';
div.style.backgroundImage='url(images/closb.gif)';
div.style.zIndex = 100003;
div.style.right = 10;
div.style.top = 20;
div.style.width = '82px';
div.style.height= '30px';
div.title='Close';
div.style.cursor='hand';
div.onclick=function(){//Click time to close the mask
fnDaoHangBgClose();
};
$('divDaoHangBg').appendChild(div);
}
$('divDaoHangBgIframe').style.display='block';
$('divDaoHangBg' ).style.display='block';
}
//Close the mask
function fnDaoHangBgClose()
{
if(!$('divDaoHangBg')){return;}
if(!$('divDaoHangBgIframe')){return;}
$('divDaoHangBgIframe').src='';
$('divDaoHangBgIframe').style.display='none';
$('divDaoHangBg').style.display='none';
}
//Call, embedded url
function fnDaoHangBgShow(url)
{
fnDaoHangBg() ;
$('divDaoHangBgIframe').src=url;
}

where $() and $C() respectively represent
$(id), get the id Object, document.getElementById(id)
$C(tag), create a tag, document.createElement(tag);