redux-compose-reducers

Summary:

chains together a series of reducer functions through functional composition

Installation:

npm install --save '@warren-bank/redux-compose-reducers'

Usage Example:

const composeReducers = require('@warren-bank/redux-compose-reducers')

const reducer_1 = (state, action) => state + 1
const reducer_2 = (state, action) => state - 1

const reducer_chain_1 = composeReducers(reducer_1, reducer_2)             // (state, action) => state + 1 - 1
const reducer_chain_2 = composeReducers(reducer_chain_1, reducer_1)       // (state, action) => state + 1 - 1 + 1
const reducer_chain_3 = composeReducers(reducer_chain_1, reducer_2)       // (state, action) => state + 1 - 1 - 1
const reducer_chain_4 = composeReducers(reducer_chain_2, reducer_chain_3) // (state, action) => state + 1 - 1 + 1 + 1 - 1 - 1

expect( reducer_1(      5, {}) ).toBe(6)
expect( reducer_2(      5, {}) ).toBe(4)

expect( reducer_chain_1(5, {}) ).toBe(5)
expect( reducer_chain_2(5, {}) ).toBe(6)
expect( reducer_chain_3(5, {}) ).toBe(4)
expect( reducer_chain_4(5, {}) ).toBe(5)

Browser Build (transpiled to ES5):

• files in repo:

  • minified javascript
  • source map

• files hosted in CDN:

  • minified javascript
  • source map

• run the usage example:

  • unit tests w/ mocha

• global variable(s):

  • window.composeReducers

Related Works:

• https://github.com/micro-js/compose-reducers

  • same outcome
  • different methodology
    • calls each reducer in a loop
      • doesn't use functional composition

• https://github.com/palantir/redoodle

  • nearly identical to @micro-js/compose-reducers
  • adds TypeScript definitions
    • restricts input/output value types
      • disallows the "composed" reducer to be used for initialization
        • state cannot be undefined

Legal:

• copyright: Warren Bank
• license: GPL-2.0