compose()

compose(...functions)

Composes functions from right to left.

This is a functional programming utility, and is included in Redux as a convenience.

You might want to use it to apply several store enhancers in a row.

Arguments

1. (arguments): The functions to compose. Each function is expected to accept a single parameter. Its return value will be provided as an argument to the function standing to the left, and so on. The exception is the right-most argument which can accept multiple parameters, as it will provide the signature for the resulting composed function.

Returns

(Function): The final function obtained by composing the given functions from right to left.

Example

This example demonstrates how to use compose to enhance a store with applyMiddleware and a few developer tools from the redux-devtools package.

import { createStore, combineReducers, applyMiddleware, compose } from 'redux'
import thunk from 'redux-thunk'
import DevTools from './containers/DevTools'
import reducer from '../reducers/index'

const store = createStore(
  reducer,
  compose(
    applyMiddleware(thunk),
    DevTools.instrument()
  )
)

Tips

• All compose does is let you write deeply nested function transformations without the rightward drift of the code. Don't give it too much credit!