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useReducer

An alternative to useState.

useReducer is usually preferable to useState when you have complex state logic that involves multiple sub-values. It also lets you optimize performance for components that trigger deep updates because you can pass dispatch down instead of callbacks.

function useReducer<S, A>(reducer: Reducer<S, A>, initialState: S): [S, Dispatch<A>];

function useReducer<S, A, I>(

reducer: Reducer<S, A>,

initialArg: I,

init: (arg: I) => S,

): [S, Dispatch<A>];

useReducer<S, A>(reducer: Reducer<S, A>, initialState: S): [S, Dispatch<A>]

An alternative to useState.

useReducer is usually preferable to useState when you have complex state logic that involves multiple sub-values. It also lets you optimize performance for components that trigger deep updates because you can pass dispatch down instead of callbacks.

§Type Parameters

S

A

§Parameters

reducer: Reducer<S, A>

Given the current state and an action, returns the new state

initialState: S

The initial value to store as state

§Return Type

[S, Dispatch<A>]

useReducer<S, A, I>(reducer: Reducer<S, A>, initialArg: I, init: (arg: I) => S): [S, Dispatch<A>]

An alternative to useState.

useReducer is usually preferable to useState when you have complex state logic that involves multiple sub-values. It also lets you optimize performance for components that trigger deep updates because you can pass dispatch down instead of callbacks.

§Type Parameters

S

A

I

§Parameters

reducer: Reducer<S, A>

Given the current state and an action, returns the new state

initialArg: I

The initial argument to pass to the init function

init: (arg: I) => S

A function that, given the initialArg, returns the initial value to store as state

§Return Type

[S, Dispatch<A>]