---
title: JSObjectFinalizeCallback
framework: javascriptcore
role: symbol
role_heading: Type Alias
path: javascriptcore/jsobjectfinalizecallback
---

# JSObjectFinalizeCallback

The callback type for finalizing an object (preparing it for garbage collection).

## Declaration

```swift
typealias JSObjectFinalizeCallback = (JSObjectRef?) -> Void
```

## Parameters

- `object`: The doc://com.apple.javascriptcore/documentation/JavaScriptCore/JSObjectRef to finalize.

## Discussion

Discussion You can finalize an object on any thread. If you name your function Finalize, you declare it like this: void Finalize(JSObjectRef object); The system calls the finalize callback on the most-derived class first, and the least-derived class (the parent class) last. You must not call any function that may cause a garbage collection or an allocation of a garbage collected object from within a JSObjectFinalizeCallback. This includes all functions that have a JSContextRef parameter.

## See Also

### Managing Callbacks

- [initialize](javascriptcore/jsclassdefinition/initialize.md)
- [JSObjectInitializeCallback](javascriptcore/jsobjectinitializecallback.md)
- [finalize](javascriptcore/jsclassdefinition/finalize.md)
- [hasProperty](javascriptcore/jsclassdefinition/hasproperty.md)
- [JSObjectHasPropertyCallback](javascriptcore/jsobjecthaspropertycallback.md)
- [getProperty](javascriptcore/jsclassdefinition/getproperty.md)
- [JSObjectGetPropertyCallback](javascriptcore/jsobjectgetpropertycallback.md)
- [setProperty](javascriptcore/jsclassdefinition/setproperty.md)
- [JSObjectSetPropertyCallback](javascriptcore/jsobjectsetpropertycallback.md)
- [deleteProperty](javascriptcore/jsclassdefinition/deleteproperty.md)
- [JSObjectDeletePropertyCallback](javascriptcore/jsobjectdeletepropertycallback.md)
- [getPropertyNames](javascriptcore/jsclassdefinition/getpropertynames.md)
- [JSObjectGetPropertyNamesCallback](javascriptcore/jsobjectgetpropertynamescallback.md)
- [callAsFunction](javascriptcore/jsclassdefinition/callasfunction.md)
- [JSObjectCallAsFunctionCallback](javascriptcore/jsobjectcallasfunctioncallback.md)