side-effects

Adds side-effects to redux, heavily inspired by redux-loop.
I rewrote it because of the lack of documentation, the lack of typescript definitions, and the fact that
testability has been dropped.

The only reason why you'd want to return a side effect from your reducer rather than just making a side effect
happen is so that you can test them. This library also decouples the effect result from the description of the
effect.

Installation

$ yarn add side-effects

## Overview

A side effect is basically the equivalent of an action - that is, it is a description of behaviour. The side-effect
equivalent of a reducer, the function that makes the side effect happen, is called an _effector_.

Effector functions make the side effects happen, and optionally return an action or a promise for an action (or actions).

You might find it useful to create side effect creator functions, similar to action creators.

Example

Here is an example of a logging side effect:

``js
import { createStore } from 'redux';
import { installSideEffects } from 'side-effects';

function loggingEffector(effect) {
switch (effect.type) {
case 'LOG':
console.log(effect.message);
break;
}
}

function reducer(state, action) {
switch (action.type) {
case 'DO_A_THING':
return [
{...state, frobblesAligned: true},
{type: 'LOG', message: 'frobbles aligned'}
];

default:
return state;
}
}

const store = createStore(reducer, installSideEffects(loggingEffector));
`

To make a side effect, just return a tuple, with the new state as the first element and the side
effect as the second.

Here's a more useful example, using promises:

`js
import { createStore } from 'redux';
import { installSideEffects } from 'side-effects';

function apiEffector(effect) {
switch (effect.type) {
case 'GET':
return fetch(effect.url)
.then((response) => response.json())
.then((result) => ({
type: 'RESPONSE_READY',
result
}));
}
}

function reducer(state, action) {
switch (action.type) {
case 'FETCH_WIDGETS':
return [
{...state, loading: true},
{type: 'GET', url: '/api/widgets'}
];

case 'RESPONSE_READY':
return {
...state,
loading: false,
widgets: action.result
};

default:
return state;
}
}

const store = createStore(reducer, installSideEffects(apiEffector));
`

API

$3

Returns an enhancer to pass to createStore. The effector is a function which makes the side
effect happen. It's much like a reducer in that it'll probably do a switch on the effect type, but
it returns an action or a promise for an action.

$3

Determines if the given object has a side effect (duck typing, can't know for sure).

$3

Replaces redux's combineReducers - this one is side effect aware. It can accept an aribtrarily deep nesting of reducer maps and multiple arguments,
either reducer functions or more maps.

$3

Creates a dummy side effect with type equal to 'none', in case you want to keep your reducers consistent.

$3

Creates a side effect which represents multiple other side effects. If serial` is true, the effects will be run in serial; that is, the following ones will only run when previous
promises have resolved.

$3

A utility effect whose effector just immediately returns the action(s) passed. Useful for dispatching other actions from a reducer.