create-reducer-extra
v0.2.0
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Reduce boilerplate in your redux reducers
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create-reducer-extra
A few helpful utilities for creating boilerplate-free Redux reducers with first class support for Typescript
Installation
yarn add create-reducer-extra
Or using npm
npm install --save create-reducer-extra
Usage
// actions.ts
import { action } from 'create-reducer-extra'
export const actionA = (someNumber) => ({ type: 'A', payload: someNumber })
export const actionB = (someString) => ({ type: 'B', payload: someString })
export const actionC = (someBool) => action('C', someBool)
// reducer.ts
import { createReducer } from 'create-reducer-extra'
const initialState = { counter: 0 }
export const reducer = createReducer<State, HandledActions>(initialState, {
A: (state, payload) => ({ counter: state.counter + payload[0] }),
B: (state, payload) => ({ counter: state.counter + Number(payload) }),
C: (state, payload) => ({ counter: payload ? state.counter + 1 : state.counter - 1 }),
})
API
Note that all of the createReducer functions:
- Expects actions to be of the form
{ type: string, payload: any }
- Your your handler functions will be called directly with the payload of the action
action
A tiny utility for creating actions in the format createReducer
expects
// actions.ts
import { action } from 'create-reducer-extra'
const changeName = (name) => action('ChangeName', { newName: name })
changeName('Fluffy') // { type: 'ChangeName', payload: { newName: 'Fluffy' } }
createMergeReducer
Allows you to only specify what has changed in your reducing function, e.g
import { createMergeReducer } from 'create-reducer-extra'
const initialState = {
animals: ['ant', 'bat'],
counter: 2,
}
const reducer = createMergeReducer(initialState, {
Add: ({ counter }, incrementAmount) => ({ counter: counter + incrementAmount}),
NewAnimals: ({ animals }, newAnimals) => ({ animals: [...animals, ...newAnimals] }),
})
reducer(initialState, { payload: 5, type: 'Add' })
// { counter: 7, animals: ['ant', 'bat'] }
reducer(initialState, { payload: ['cat', 'dog'], type: 'NewAnimals' })
// { counter: 2, animals: ['ant', 'bat', 'cat', 'dog] }
createReducer
For when you want to specify exactly what the next state will be
import { createReducer } from 'create-reducer-extra'
const initialState = {
animals: ['ant', 'bat'],
counter: 2,
}
const reducer = createReducer(initialState, {
Add: ({ counter }, incrementAmount) => ({ counter: counter + incrementAmount}),
NewAnimals: ({ animals, counter }, newAnimals) => ({ animals: [...animals, ...newAnimals], counter }),
})
reducer(initialState, { payload: 3, type: 'Add' })
// { counter: 5 }
// Note the missing 'animals' property
createResettableReducer
Provides the ability to reset a reducer to its initial state.
This can be useful for handling things such as a logout in a single page app.
The ResetState can be overridden in the handler to provide custom behaviour.
import { createResettableReducer, resetState } from 'create-reducer-extra'
const initialState = { animals: ['ant', 'bat'], counter: 2 }
const reducer = createResettableReducer(initialState, {
Add: ({ counter }, incrementAmount) => ({ counter: counter + incrementAmount}),
NewAnimals: ({ animals }, newAnimals) => ({ animals: [...animals, ...newAnimals] }),
})
const nextState = reducer(initialState, { payload: 5, type: 'Add' })
// { counter: 7, animals: ['ant', 'bat'] }
reducer(nextState, resetState())
// { animals: ['ant', 'bat'], counter: 2 } === initialState
createResetMergeReducer
Combines the functionality of createMergeReducer and createResettableReducer.
Note that if the ResetState action is handled by the reducer, the result returned will be merged into the current state e.g.
import { createResetMergeReducer, resetState } from 'create-reducer-extra'
const initialState = { animals: ['ant', 'bat'], counter: 2 }
const reducer = createResetMergeReducer(initialState, {
Add: ({ counter }, incrementAmount) => ({ counter: counter + incrementAmount}),
[ResetState]: ({ animals }) => ({ animals: [] }),
})
const nextState = reducer(initialState, resetState())
// { counter: 2, animals: [] }
Usage with Typescript
This library leverages some new features introduced in Typescript 2.8 to provide complete type safety with minimal boilerplate. To take advantage of completely type-safe reducers you need to:
- Define your action creators
// actions.ts
import { action, Action } from 'create-reducer-extra'
const actionA = (param: Array<number>): Action<'A', Array<number>> =>
({ type: 'A', payload: param })
const actionB = (param: string): Action<'B', string> => ({ type: 'B', payload: param })
const actionC = () => action('C', false)
- In your reducer create:
- A type to represent the state of the reducer
- A type to represent the actions your reducer should handled
- Provide those as type parameters to your reducer-creator of choice:
// reducer.ts
import { createReducer } from 'create-reducer-extra'
import * as actions from './actions'
type State = { counter: number }
type HandledActions = typeof actions
const reducer = createReducer<State, HandledActions>(initialState, {
A: (state, payload) => ({ counter: state.counter + payload[0] }),
B: (state, payload) => ({ counter: state.counter + Number(payload) }),
C: (state, payload) => ({ counter: payload ? state.counter + 1 : state.counter - 1 }),
})
Voila, everything is type-safe!