Function derived

derived<S extends Stores, T>(
    stores: S,
    fn: (
        values: StoresValues<S>,
        set: (value: T) => void,
        update: (fn: Updater<T>) => void,
    ) => void | Unsubscriber,
    initial_value?: T,
): Readable<T>
Derived value store by synchronizing one or more readable stores and applying an aggregation function over its input values.
Type Parameters
- S extends Stores
- T
Parameters
- stores: S
- fn: (
      values: StoresValues<S>,
      set: (value: T) => void,
      update: (fn: Updater<T>) => void,
  ) => void | Unsubscriber
- Optionalinitial_value: T
Returns Readable<T>
derived<S extends Stores, T>(
    stores: S,
    fn: (values: StoresValues<S>) => T,
    initial_value?: T,
): Readable<T>
Derived value store by synchronizing one or more readable stores and applying an aggregation function over its input values.
Type Parameters
- S extends Stores
- T
Parameters
- stores: S
- fn: (values: StoresValues<S>) => T
- Optionalinitial_value: T
Returns Readable<T>