rezz

Composable, chainable reducer toolkit for redux

Installation

npm install --save rezz

or

yarn add rezz

Introduction

rezz is a toolkit that creates functions that are chainable, composable, and accept redux-style arguments: state and action. rezz never mutates any data, allowing you to know if state has been modified with a simple equality check.

rezz is primarily intended to be used with redux, though it's not required. Use it like this:

import createReducerCreator from 'rezz/createReducerCreator';
import addToList from 'rezz/addToList';
import removeFromList from 'rezz/removeFromList';
  
export default createReducerCreator()(
    addToList('ADD_TO_LIST'),
    removeFromList('REMOVE_FROM_LIST')
);    

This reducer will listen for actions with ADD_TO_LIST type and add the data to a list, and listen for REMOVE_FROM_LIST and remove from that list. Import this reducer and use it as normal with redux or elsewhere. There are three primary types of functions available:

• createReducerCreator allows you to combine multiple reducers together with a common set of options.
• Combiners are methods that accept a list of reducers and return a reducer that combine those reducers in some way, such as chaining them together, or prioritizing one over another.
• Operators are reducer creators that perform actual, simple, low-level operations based on a state and action. They accept a string or array determining what type actions to activate on.

API

createReducerCreator(options: ReducerOptions) => ReducerCreator

A simple wrapper that returns a reducer creator and provides the options to all the reducers.

ReducerOptions

These options determine how all the reducers passed to the reducer creator act.

{
    initialState: any,
    combiner: Combiner,
    equalityCheck: <T>(a: T, b: T) => boolean,
    payloadStrategy: (action: Action) => any,
    keyStrategy: (action: Action) => any,
}

• initialState (default null): The state the reducer starts with.
• combiner (default chainCombiner): A function that accepts a list of reducers and options, and returns a single reducer that combines the list of reducers. By default, it uses chainCombiner that simply runs the reducers one after another.
• equalityCheck (default (a, b)=>a===b): A function that is used when a reducer needs to determine if two items in a list or collection are equal.
• payloadStrategy (default action => action.payload): A function that takes a redux-like action and returns the relevant payload.
• keyStrategy (default action => action.key): A function that takes a redux-like action and returns the relevant key.

ReducerCreator(...reducers: Reducer) => Reducer

Each argument is a reducer that will be combined into a single reducer.

Combiners

chainCombiner(Array<Reducer>, options: ReducerOptions) => Reducer

Combines the provided reducers by running them one after another in the provided order.

Operators

Operators create simple reducers. The first argument to an operator is either an array of strings, or a string. If it's not either, the toString method will be called on it, so you can pass actions created by redux-actions for example.

Array Operators

addToList

Adds the provided data to the state using Array's concat method, so the data can be an array or a single item. If the state is not currently an array, then the data becomes the state.

removeFromList

Removes the provided data from the list if present, using the equailityCheck option to determine what to remove.

updateInList

Shorthand for removeFromList followed by addToList.

Object/Collection Operators

set

Sets a property on the state to a value. The property being set is determined by options.keyStrategy. The value is determined by options.valueStrategy.

assign

Assigns the state to the value determined by options.valueStrategy.