Function derived

derived<S, T>(stores, fn, initial_value?): 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)
  - - (values, set, update): void | Unsubscriber
    - Parameters
      values: StoresValues<S>
      set: ((value: T) => void)
      (value): void
      Parameters
      value: T
      Returns void
      update: ((fn: Updater<T>) => void)
      (fn): void
      Parameters
      fn: Updater<T>
      Returns void
      Returns void | Unsubscriber
- Optionalinitial_value: T
Returns Readable<T>
derived<S, T>(stores, fn, initial_value?): 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)
  - - (values): T
    - Parameters
      values: StoresValues<S>
      Returns T
- Optionalinitial_value: T
Returns Readable<T>