import { createSlice } from '@reduxjs/toolkit'; export const counterSlice = createSlice({ name: 'counter', initialState: { value: 0, }, reducers: { increment: state => { // Redux Toolkit allows us to write "mutating" logic in reducers. It // doesn't actually mutate the state because it uses the Immer library, // which detects changes to a "draft state" and produces a brand new // immutable state based off those changes state.value += 1; }, decrement: state => { state.value -= 1; }, incrementByAmount: (state, action) => { state.value += action.payload; }, }, }); export const { increment, decrement, incrementByAmount } = counterSlice.actions; // The function below is called a thunk and allows us to perform async logic. It // can be dispatched like a regular action: `dispatch(incrementAsync(10))`. This // will call the thunk with the `dispatch` function as the first argument. Async // code can then be executed and other actions can be dispatched export const incrementAsync = amount => dispatch => { setTimeout(() => { dispatch(incrementByAmount(amount)); }, 1000); }; // The function below is called a selector and allows us to select a value from // the state. Selectors can also be defined inline where they're used instead of // in the slice file. For example: `useSelector((state) => state.counter.value)` export const selectCount = state => state.counter.value; export default counterSlice.reducer;