React state management with Redux and MobX

React State Management
with Redux and MobX
DARKO KUKOVEC @DarkoKukovec
ANDREI ZVONIMIR CRNKOVIĆ @andreicek
INFINUM @inﬁnumco

DARKO KUKOVEC
JS Team Lead
@DarkoKukovec
ANDREI ZVONIMIR CRNKOVIĆ
JS Emojineer
@andreicek

We're an independent
design & development
agency.

Topic
Time
SCHEDULE
13:45-14:30 14:30-15:15 15:15-16:00
React setState React + Redux React + MobX
The Joy of Optimizing
Una Kravets (DigitalOcean)
Coﬀee.js? How I hacked my
coﬀee machine using
JavaScript
Dominik Kundel (Twilio)
GraphQL: Data in modern
times
Dotan Simha (The Guild)

APP STATE
• Data
• Which user is logged in?
• Which todos did the user create?
• UI
• Which todos is the user looking at (ﬁlter - all, complete, incomplete)

STATE MANAGEMENT
• What should happen when some data changes?
• Does the UI need to be updated
• Does some other data depend on it?
• Does the app need to make an action (e.g. API call)?

IMAGE GOES INSIDE THIS BOX
DELETE BOX AFTER PLACING IMAGE

• Todos
• Title
• Status
• Active ﬁlter
• Number of todos

Handing an action in the app
• The user checks a todo as complete

• Mark the todo as complete

• Update the incomplete items count

• What ﬁlter is active again?

• What ﬁlter is active again?
• Do I need to update the list of todos?
• Add/remove item?
• Sort items?
• Should I show an empty state?
• Should I make an API call?
• Should I save the change into
localStorage?

Data Flow in JavaScript Applications - Ryan Christiani

EXAMPLE PROJECT
• Tech conference app
• Fetch talk list (async action)
• Favourite talks (simple sync action)
• Filter by location (ﬁltering data from the state)
• To simplify
• No routing
• No forms
• Not responsive
• Only basic styling
• Assumption: Browsers support Fetch API
• 70% of browsers do, polyﬁll available for the rest

EXAMPLE PROJECT - TECH STUFF
• create-react-app as the initial setup
• https://github.com/inﬁnum/shift-2017

COMPONENT TYPES
Container Presenter
Usually root components Inside of container components
No UI Only UI
State of children components Dumb component
Handle state changes "Data down, actions up"

PREREQUISITES
• A modern IDE (VS Code, Sublime Text, Atom, Webstorm or similar)
• Latest version of Chrome/Chromium for debugging
• Node.js 6 or 7
• npm 4 or yarn

REACT + SETSTATE
• No central state
• Every component contains its (and children?) state
• State changes are async! - 2nd argument is a callback
• Component is re-rendered unless shouldComponentUpdate() returns false
• Additional libs
• react-addons-update

// Code time!
// setState
// Code used for setup:
create-react-app app-setstate
npm install --save react-addons-update
v1.0

* Mock data
* Styles
* Presenter components
* Utils
v1.0

// Container component state
v1.1

FUNCTIONAL SETSTATE
• Since React 15?
• Will eventually replace the usage with objects as the ﬁrst argument

class App extends Component {
constructor(props) {
super(props);
this.state = {counter: 0};
}
increaseCounter() {
this.setState({
counter: this.state.counter + 1
});
}
decreaseCounter() {
this.setState((prevState, props) => {
return {counter: prevState.counter + 1};
});
}
render() {
// ...
}
}

SCALING SETSTATE
• A bad idea
• One master component with app state
• Some smaller independent containers

http:!//!!www.timqian.com/star-history/#mobxjs/mobx&reactjs/redux&facebook/flux&facebook/relay

ADVANTAGES
Easier to (unit) test
MobX Redux
Faster
Less boilerplate Smaller
Time travelMore ﬂexible
Easier to debug?Simpler async actions

IN THE NUTSHELL...
https:!//twitter.com/phillip_webb/status/705909774001377280

USAGE
MobX Redux
mobx-react react-redux
Not React dependent Not React dependent
mobx-angular
Python
GWT

REACT + REDUX
• One central state
• Additional libs
• redux
• react-redux
• redux-thunk

ACTIONS
Payloads of information that send data from your
application to your store

REDUCERS
Specify how the application's state changes in
response to actions

import { createStore } from 'redux'
function counter(state = 0, action) {
switch (action.type) {
case 'INCREMENT':
return state + 1
case 'DECREMENT':
return state - 1
default:
return state
}
}
let store = createStore(counter)
store.subscribe(() =>
console.log(store.getState())
)
store.dispatch({ type: 'INCREMENT' })
// 1
// 2
store.dispatch({ type: 'DECREMENT' })
// 1
THE GIST

// Code time!
// Redux
create-react-app app-redux
npm install --save redux react-redux redux-thunk
v2.0

* Mock data
* Styles
* Utils
v2.0

// Redux DevTools
// https://chrome.google.com/webstore
https:!//chrome.google.com/webstore/detail/redux-devtools/lmhkpmbekcpmknklioeibfkpmmfibljd?hl=en
v2.6

SCALING REDUX
• Only one store!
• Multiple (nested) reducers, actions
• Store data nesting === reducer nesting
• "reducers" folder, "actions" folder
• Folders based on functionality
• e.g. "orders" contains a orders reducer, orders actions and all other related stuﬀ

THINGS TO KEEP IN MIND
• NEVER mutate the state!
• Immutable.js

IMMUTABLE.JS
• https://github.com/facebook/immutable-js/
• List, Stack, Map, OrderedMap, Set, OrderedSet, Record
• Nested structures

REDUX FORM
• https://github.com/erikras/redux-form
• Uses Immutable.js
• Sync/async validations
• Wizard forms

REDUX - THE SOURCE CODE
https:!//twitter.com/bloodyowl/status/740228059538857984

REACT + MOBX
• One/multiple states
• Additional libs
• mobx
• mobx-react

Anything that can be derived from the application
state, should be derived. Automatically.
- The philosophy behind MobX

OBSERVABLE
Your state
e.g., list of TODOs

ACTION
A function that changes the state
e.g., function called after the user clicks on the
completed checkbox

COMPUTED PROPERTY
A value derived from your state
e.g., list of completed TODOs

OBSERVER
Function (component?) that needs to be updated
on state change
e.g., component showing a list of TODOs

STATE
(OBSERVABLES)
COMPUTED
PROPS
OBSERVERSACTION
UPDATES
UPDATES
UPDATES
CHANGES

THE GIST
import { observable, autorun } from 'mobx';
const store = observable({counter: 0});
autorun(() =>
console.log(store.counter);
);
store.counter++;
// 1
store.counter++;
// 2
store.counter--;
// 1

import { createStore } from 'redux'
function counter(state = 0, action) {
switch (action.type) {
case 'INCREMENT':
return state + 1
case 'DECREMENT':
return state - 1
default:
return state
}
}
let store = createStore(counter)
store.subscribe(() =>
console.log(store.getState())
)
// 1
// 2
store.dispatch({ type: 'DECREMENT' })
// 1
THE GIST
import { observable, autorun } from 'mobx';
const store = observable({counter: 0});
autorun(() =>
console.log(store.counter);
);
store.counter++;
// 1
store.counter++;
// 2
store.counter--;
// 1
MobX Redux

DECORATORS
JS proposed feature (Babel plugin)
TypeScript feature

import {observable, computed} from 'mobx';
class Todos {
@observable list = [];
users = observable([]);
@computed get complete() {
return this.list.filter((todo) => todo.complete);
}
incomplete: computed(() => {
return this.list.filter((todo) => !todo.complete);
})
}

// Code time!
// MobX
create-react-app app-mobx --scripts-version
custom-react-scripts
npm install --save mobx mobx-react
v3.0

* Mock data
* Styles
* Utils
v3.0

THINGS TO KEEP IN MIND
• use extendObservable to add properties to an object
• Wrapped objects - isArray(arr) or array.is(toJS(arr))
• Don't be afraid to use observers
• If done right: More observers → better performance

SCALING MOBX
• Your code can be object oriented!
• A list of best practices
• Strict mode, actions (transactions)
• Use helper libs

MOBX-REACT-DEVTOOLS
• Log actions & reactions
• Check dependencies for a react component
• Show update times

MOBX-COLLECTION-STORE
• https://github.com/inﬁnum/mobx-collection-store
• One collection, multiple model types
• Relationships between models
• mobx-jsonapi-store
• https://github.com/inﬁnum/mobx-jsonapi-store

MOBX-STATE-TREE
• https://github.com/mobxjs/mobx-state-tree
• Made by MobX authors
• v1.0 release soon
• Supports snapshots, replay, JSON patches, etc.
• Supports time travel!
• Compatible with Redux DevTools!

MOBX-REACT-FORM
• https://github.com/foxhound87/mobx-react-form
• Dedicated DevTools: https://github.com/foxhound87/mobx-react-form-devtools

REACT SETSTATE + MOBX
• You can still use it
• But, you can also do this…

import {observable} from 'mobx';
import {observer} from 'mobx-react';
import React, {Component} from 'react';
@observer
export default class Foo extends Component {
@observable state = {
clickCount = 0;
};
onClick: () => {
this.state.clickCount++; // if you use setState it will stop being an observable!
}
render() {
return (
<button onClick={this.onClick}>
{
this.state.clickCount ? `Clicked ${this.state.clickCount} times!` : 'Click me!'
}
</button>
);
}
}

RESOURCES
• Redux
• http://redux.js.org/
• https://egghead.io/courses/getting-started-with-redux
• https://egghead.io/courses/building-react-applications-with-idiomatic-redux
• MobX
• https://mobx.js.org/
• https://mobxjs.github.io/mobx/getting-started.html
• https://egghead.io/courses/manage-complex-state-in-react-apps-with-mobx

Visit infinum.co or find us on social networks:
infinum.co infinumco infinumco infinum
Thank you!
DARKO@INFINUM.CO
@DARKOKUKOVEC
ANDREI@INFINUM.CO
@ANDREICEK

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