Access the private data field of an object.
Syntax
void * JS_GetPrivate(JSObject *obj);
Name | Type | Description |
---|---|---|
obj |
JSObject * |
An object whose JSClass has the JSCLASS_HAS_PRIVATE flag. |
Description
JS_GetPrivate
accesses an object's private data field. obj
must be an instance of a class that has the JSCLASS_HAS_PRIVATE
flag.
New objects' private data fields are initially NULL
.
If obj
is a Function
object, as reported by JS_ObjectIsFunction
, the private data is a pointer to a JSFunction
. (But consider using JS_ValueToFunction
instead to access it.)
Warning: It is dangerous to call JS_GetPrivate
on a JSObject *
unless the object's JSClass
is known. If the object is not of the expected JSClass
, the result of JS_GetPrivate
would probably be NULL
or a pointer to some unexpected type of data. Casting that pointer to the desired type and using it could then cause a crash or worse.
Getters, setters, and methods of custom classes should use JS_GetInstancePrivate
instead to avoid this danger. However, it is safe to use JS_GetPrivate
in a finalizer
.