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This feature is obsolete.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.
Determines if a given jsval is the JavaScript value undefined.
Syntax
JSVAL_IS_VOID(v)
Description
JSVAL_IS_VOID(v) is true if v is JSVAL_VOID, which represents the JavaScript value undefined.
Example
The following code snippet illustrates how a JavaScript variable, MyItem, is conditionally tested in an if statement to see if it is void.
if (JSVAL_IS_VOID(MyItem)) {
...
}