Serializable object

Serializable objects are objects that can be serialized and later deserialized in any JavaScript environment ("realm"). This allows them to, for example, be stored on disk and later restored, or cloned with structuredClone(), or shared between workers using DedicatedWorkerGlobalScope.postMessage().

The serialization may not include all the properties and other aspects of the original object. For example, a serialization of a DOMException must include the name and message properties, but whether it includes other properties is implementation dependent. As a result, a deserialized object may not be an identical clone/copy of the original object. The new deserialized object will however be a deep copy, so any properties that were serialized from the original object and then deserialized into the new object will share no references with the original object.

In some cases when serializing and deserializing an object, it makes sense to transfer some resources rather than creating a copy. Objects that can be transferred are called Transferable objects.