# JSManagedValue A JavaScript value with conditional retain behavior to provide automatic memory management. ``` class JSManagedValue ``` ## Overview The primary use case for a managed value is to store a JavaScript value in an Objective-C or Swift object that exports to JavaScript. > Important: > Don’t store a nonmanaged ``doc://com.apple.javascriptcore/documentation/JavaScriptCore/JSValue`` object in a native object that exports to JavaScript. Because a ``doc://com.apple.javascriptcore/documentation/JavaScriptCore/JSValue`` object references its enclosing ``doc://com.apple.javascriptcore/documentation/JavaScriptCore/JSContext`` object, this action creates a retain cycle, preventing deallocation of the context. A managed value’s *conditional retain* behavior ensures retention of its underlying JavaScript value as long as either of the following conditions is true: - The JavaScript value is reachable through the JavaScript object graph (that is, not subject to JavaScript garbage collection). - The [`JSManagedValue`](/documentation/JavaScriptCore/JSManagedValue) object is reachable through the Objective-C or Swift object graph, as you report to the JavaScriptCore virtual machine using the [`addManagedReference(_:withOwner:)`](/documentation/JavaScriptCore/JSVirtualMachine/addManagedReference(_:withOwner:)) method. However, if neither of these conditions is true, the managed value sets its [`value`](/documentation/JavaScriptCore/JSManagedValue/value) property to `nil`, releasing the underlying [`JSValue`](/documentation/JavaScriptCore/JSValue) object. > Note: > On its own, a ``doc://com.apple.javascriptcore/documentation/JavaScriptCore/JSManagedValue`` object behaves similarly to an ARC weak reference to its underlying ``doc://com.apple.javascriptcore/documentation/JavaScriptCore/JSValue`` object—that is, if you don’t use the ``doc://com.apple.javascriptcore/documentation/JavaScriptCore/JSVirtualMachine/addManagedReference(_:withOwner:)`` method to add conditional retain behavior, the managed value’s ``doc://com.apple.javascriptcore/documentation/JavaScriptCore/JSManagedValue/value`` property automatically becomes `nil` when the JavaScript garbage collector destroys the underlying JavaScript value. ## Topics ### Creating a Managed Value [`init(value:)`](/documentation/JavaScriptCore/JSManagedValue/init(value:)) Initializes a managed value with the specified JavaScript value. [`managedValueWithValue:`](/documentation/JavaScriptCore/JSManagedValue/managedValueWithValue:) Creates a managed value with the specified JavaScript value. [`init(value:andOwner:)`](/documentation/JavaScriptCore/JSManagedValue/init(value:andOwner:)) Creates a managed value and associates it with an owner. ### Accessing the Managed Value [`value`](/documentation/JavaScriptCore/JSManagedValue/value) The managed value’s underlying JavaScript value. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)