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; 
}

需要充分测试