The Yahoo Global Object includes several useful type-checking methods in the YAHOO.lang object.  Click the Check button in each row to evaluate the data.
| Data | isObject | isArray | isFunction | 
|---|---|---|---|
| null | |||
| [] or new Array() | |||
| {} or new Object() | |||
| function Foo() {} | |||
| new Foo() | |||
| elem.getElementsByTagName('p') | |||
| YAHOO.util.Dom.
                        getElementsByClassName( | |||