Selector
A selector is a function used to compute state derivations. Selectors are often used as adapters that take a store's state object and pluck a piece off of it.
Selectors have many benefits:
They are declarative -
selectHighestBid(),selectCurrentWeapon(), etc...They are abstract -
selectTodos(state)vsstate.entities.todos.They compose well. Selectors can be used as input to other selectors.
They can be memoized to prevent unnecessarily repeating heavy calculations. Zedux provides support for memoized selectors out of the box. See the
select()api.
Even small applications can benefit immensely from selectors. This is why they are included as part of Zedux core. 'Cause where would a complete state management tool be without them?
Definition
interface Selector<S = any, D = any> {
(state: S, ...args: any[]): D
}
state - The current state of the store.
Notes
The Zedux implementation of selectors is basically a stripped-down version of the excellent reselect library. However, Zedux doesn't implement everything. If you need any of the extra features provided by reselect, feel free to use it! Any existing Zedux selectors will port over nicely.