判断目标是否是window,document,和拥有tagName的Element的代码

function isWindow( obj )
{
if( typeof obj.closed == undefined ) return false;
var result = /\[object (window|global)\]/i.test( Object.prototype.toString.call( obj ) );
if( result )return result;
try{
obj.closed = obj.closed;
return false;
}catch(e)
{
result = true;
}
return result;
}
function isDocument( obj )
{
if( typeof obj.body == undefined ) return false;
var b = obj.body;
try{
obj.body = null;
obj.body = b;
return false;
}catch(e)
{
return true;
}
}
function isElement( o )
{
var tn = tagName,temp = o[tn],result;
if( typeof temp == undefined )return false;
try{
o[tn] = null;
result = ( temp == o[tn] );
o[tn] = temp;
return result;
}catch(e)
{
return true;
}
}

function getOwnerWindow( node )
{
if( isWindow( node ) )return node;
var doc = isDocument( node ) ? node : node.ownerDocument;
return doc.view || doc.parentWindiw || doc.defaultView;
}