Obsolete since JSAPI 32
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.
Determine if a given jsval is null.
Syntax
JSVAL_IS_NULL(v)
Description
JSVAL_IS_NULL(v) is true if v is JSVAL_NULL, which is the JavaScript null value.
(Note: JSVAL_IS_OBJECT(JSVAL_NULL)true.)
Example
The following code snippet illustrates how a JavaScript variable, MyItem, is conditionally tested in an if statement to see if it contains a null value.
if (JSVAL_IS_NULL(MyItem)) {
...
}