Function prunePersistence

dash/dash-renderer/src/persistence.js:461–530

(layout, newProps, dispatch)

 * but not for props nested inside children
 */
export function prunePersistence(layout, newProps, dispatch) {
    const {
        canPersist,
        id,
        props,
        persistence,
        persisted_props,
        persistence_type,
        element
    } = getProps(layout);

    const getFinal = (propName, prevVal) =>
        propName in newProps ? newProps[propName] : prevVal;
    const finalPersistence = getFinal('persistence', persistence);

    if (!canPersist || !(persistence || finalPersistence)) {
        return newProps;
    }

    const finalPersistenceType = getFinal('persistence_type', persistence_type);
    const finalPersistedProps = getFinal('persisted_props', persisted_props);
    const persistenceChanged =
        finalPersistence !== persistence ||
        finalPersistenceType !== persistence_type ||
        finalPersistedProps !== persisted_props;

    const notInNewProps = persistedProp =>
        !(persistedProp.split('.')[0] in newProps);

    const update = {};

    let depersistedProps = props;

    if (persistenceChanged && persistence) {
        // clear previously-applied persistence
        const storage = getStore(persistence_type, dispatch);
        forEach(
            persistedProp =>
                modProp(
                    getValsKey(id, persistedProp, persistence),
                    storage,
                    element,
                    props,
                    persistedProp,
                    update,
                    UNDO
                ),
            filter(notInNewProps, persisted_props)
        );
        depersistedProps = mergeRight(props, update);
    }

    if (finalPersistence && persistenceChanged) {
        const finalStorage = getStore(finalPersistenceType, dispatch);
        // apply new persistence
        forEach(
            persistedProp =>
                modProp(