Component Instance

The API for a mounted component instance.

How instances are created

Component instances are created from the component constructor via the mount() or mountAll() method.

For more information, see Mounting Instances.

Instance shape

The public instance currently exposes:

root

root is the resolved root element the component was mounted on.

state

state is the public reactive state object.

Properties marked private or readonly in state options are protected from external reads and/or writes.

Updating writable public properties triggers the component update flow.

For broader guidance on reactive state behavior, see State and State Update Flow.

dispose()

dispose() unmounts the instance and runs cleanup behavior.

addStateListener()

Use addStateListener() to subscribe to a specific state property.

const cleanup = instance.addStateListener('count', (event) => {
    console.log(event.newValue);
});

The listener receives an event object with the following properties:

Property	Description
property	The state property name that changed.
newValue	The incoming value for the update.
oldValue	The outgoing value for the update.
target	The mounted instance that emitted the change.

The method returns a cleanup function that removes the listener.

To learn more, see State Listeners.