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.