React, Redux and es6/7

REACT | REDUX | ES6/7
THE 2ND MPO COP
– by Jabi (Cho Dongho)

AGENDA
1. 가볍게 훑어보는 React
2. 대충 보는 Redux
3. 자주 쓰이는 ES6/7 문법
4. 알아두면 좋을 ES6 문법

React lifecycle
https://medium.com/@eddychang_86557/react-lifecycle-methods-diagram-38ac92bb6ﬀ1

React ES6 classes
https://facebook.github.io/react/docs/reusable-components.html#es6-classes
export default class Counter extends React.Component { 
constructor(props) { 
super(props); 
this.state = {
count: props.initialCount
}; 
this.tick = this.tick.bind(this); 
} 
 
tick() { 
this.setState({ count: this.state.count + 1 }); 
} 
 
render() { 
return ( 
<div onClick={this.tick}> 
Clicks: { this.state.count } 
</div> 
); 
} 
} 
 
Counter.propTypes = { 
initialCount: React.PropTypes.number 
}; 
 
Counter.defaultProps = { 
initialCount: 0 
};
export default React.createClass({ 
propTypes: { 
}, 
 
getDefaultProps: function() { 
return { 
initialCount: 0 
}; 
}, 
 
getInitialState: function() { 
return {
count: this.props.initialCount
}; 
}, 
 
tick: function() { 
}, 
 
render: function() { 
return ( 
</div> 
); 
} 
});

React ES6 classes
https://facebook.github.io/react/docs/reusable-components.html#es6-classes
export default React.createClass({ 
propTypes: { 
}, 
 
getDefaultProps: function() { 
return { 
initialCount: 0 
}; 
}, 
 
getInitialState: function() { 
return {
}; 
}, 
 
tick: function() { 
}, 
 
render: function() { 
return ( 
</div> 
); 
} 
});
export default class Counter extends React.Component { 
static propTypes = { 
}; 
 
static defaultProps = { 
initialCount: 0 
}; 
 
state = {
}; 
 
constructor(props) { 
super(props); 
this.tick = this.tick.bind(this); 
} 
 
tick() { 
} 
 
render() { 
return ( 
</div> 
); 
} 
}

React ES6 classes
METHOD BINDING
RECOMMENED
https://facebook.github.io/react/docs/reusable-components.html#no-autobinding

React ES6 classes
METHOD BINDING
RECOMMENED
https://facebook.github.io/react/docs/reusable-components.html#no-autobinding
export default class Counter extends Component { 
tick() { 
} 
render() { 
return ( 
<div onClick={::this.tick} /> 
); 
} 
}
BE CAREFUL (function bind operator)

React Performance
Props vs State
- state를가진컴포넌트는복잡도를증가시킴
- 가급적이면최상위컴포넌트를제외하고는props만으로제어
React.PureComponent
- react-addons-pure-render-mix구현
- reactv15.3.0부터사용가능
https://facebook.github.io/react/docs/pure-render-mixin.html
https://facebook.github.io/react/docs/advanced-performance.html

oﬃcial: http://redux.js.org
oﬃcial (ko): http://dobbit.github.io/redux
cartoon intro to redux:  
http://bestalign.github.io/2015/10/26/cartoon-intro-to-redux

Redux
View
Action Dispatcher
Store
React =
Redux =
View
Controller
Model

Redux
데이터의흐름이단방향
애플리케이션의모든데이터(state)는 
하나의모델(store)안에하나의객체트리구조로저장됨
데이터(state)는읽기전용

Redux
Action
Store
Reducer
- 상태의변화를위해이뤄져야할행위에대한처리
- repository에서데이터로딩등
- 액션의결과로상태를변경
- 응용프로그램의크기에따라단일또는여러리듀서로관리
- 응용프로그램의전체데이터를관리(dispatch포함)

EXAMPLE - VIEW
SummaryContainer

EXAMPLE - VIEW
SummaryContainer
SummaryList
Pagination

EXAMPLE - VIEW
SummaryContainer
SummaryList
Pagination
Summary
Summary

EXAMPLE - VIEW
SummaryContainer
SummaryList
Pagination
Summary
Summary
ProgressBar
ProgressBar

EXAMPLE - VIEW
SummaryContainer
SummaryList
Pagination
Summary
Summary
ProgressBar
ProgressBar
Download
Download

EXAMPLE - MODEL (APPLICATION STATE)
{
summaries: [
{
id: 10,
manageCode: 'baby_offline_coupon_15000',
title: '로켓배송기저귀분유물티슈',
description: '로켓배송 기저귀,분유,물티슈 카테고리 3만원 이상 구매 시 1만5천원 할인',
progress {
status: 'COMPLETED',
progress: 100
}
},
{ /* ... */ },
],
paging: {
page: 1,
size: 2,
totalPage: 5
}
}

EXAMPLE - REDUX
export function fetchSummary(params) { 
return { 
thunk: async(dispatch, getState, { repositories: { summary: repository } }) => { 
const { data: summaries } = await repository.getSummaries(params); 
const action = { type: 'UPDATE_SUMMARY', payload: summaries }; 
return dispatch(action); 
} 
}; 
}
summaryAction.js
const initialState = { 
summaries: [] 
}; 
 
export default function summaryReducer(state = initialState, action) { 
switch (action.type) { 
case 'UPDATE_SUMMARY': 
return { 
...state, 
summaries: action.payload.contents 
} 
} 
}
summaryReducer.js

EXAMPLE - REDUX
export function fetchSummary(params) { 
return { 
thunk: async(dispatch, getState, { repositories: { summary: repository } }) => { 
const { data: summaries } = await repository.getSummaries(params); 
const action = { type: 'UPDATE_SUMMARY', payload: summaries }; 
} 
}; 
}
summaryAction.js
summaries: [] 
}; 
 
export default function summaryReducer(state = initialState, action) { 
case 'UPDATE_SUMMARY': 
return { 
...state, 
summaries: action.payload.contents 
} 
} 
}
summaryReducer.js
import { combineReducers, createStore } from 'redux'; 
import summaryReducer from './summaryReducer'; 
import paginationReducer from './paginationReducer'; 
import otherReducer from './otherReducer'; 
 
const reducer = combineReducers({ 
summary: summaryReducer, 
pagination: paginationReducer, 
other: otherReducer 
}); 
 
const store = createStore(reducer);
store.js

EXAMPLE - CONTAINER
import React, { PureComponent, PropTypes } from 'react'; 
import { connect } from 'react-redux'; 
import { fetchSummary } from '../actions/summaryAction'; 
import SummaryList from ‘../components/SummaryList’; 
import Pagination from ‘../components/Pagination’; 
 
@connect(state => ({ 
summaries: state.summary.summaries, 
paging: state.pagination.paging 
}), { 
fetchSummary 
}) 
export default class SummaryContainer extends PureComponent { 
summaries: PropTypes.array.isRequired, 
paging: PropTypes.object.isRequired, 
fetchSummary: PropTypes.func.isRequired 
}; 
 
render() { 
const { summaries, paging } = this.props; 
return ( 
<div> 
<SummaryList summaries={summaries} /> 
<Pagination pagination={paging} 
onPageChange={this.props.fetchSummary} 
/> 
</div> 
); 
} 
} 
containers/SummaryContainer.js

EXAMPLE - COMPONENT
import Summary from './Summary'; 
 
export default class SummaryList extends PureComponent { 
summaries: PropTypes.array.isRequired, 
fetchSummary: PropTypes.func.isRequired 
};
 
static defaultProps = {
summaries: []
}; 
 
render() { 
const { summaries } = this.props; 
return ( 
<div> 
{ summaries.map(summary => <Summary summary={summary} />) } 
</div>  
); 
} 
} 
components/SummaryList.js

EXAMPLE - COMPONENT
import ProgressBar from './ProgressBar'; 
import Download from './Download'; 
 
export default class Summary extends PureComponent { 
summary: PropTypes.object.isRequired 
};
 
static defaultProps = { 
summary: {} 
};
 
render() { 
const { id, manageCode, title, description, progress } = this.props; 
return ( 
<div> 
<Text label="id" data={id} /> 
<Text label="manageCode" data={manageCode} /> 
<Text label="title" data={title} /> 
<Text label="description" data={description} /> 
<ProgressBar progress={progress} /> 
<Download id={id} status={progress.status} /> 
</div> 
); 
} 
}
components/Summary.js
Pagination, ProgressBar, Download 컴포넌트는 생략

개발 중에 발생했던 실수

만들려는 형태:
* 계층형카테고리구조에서앞서선택한카테고리의하위카테고리를계속해서선택

잘못된 예
export function fetchCategory(code) { 
return { 
thunk: async(dispatch, getState, { repositories: { category: repository } }) => { 
const { data: categories } = await repository.getCategoriesByCode({code}); 
const action = { type: 'UPDATE_CATEGORY', payload: categories }; 
} 
}; 
}
categoryAction.js
categories: [] 
}; 
 
export default function categoryReducer(state = initialState, action) { 
case 'UPDATE_CATEGORY': 
return { 
...state, 
categories: action.payload 
} 
} 
}
categoryReducer.js
[
{ code: 1010, name: ‘패션/의류잡화’ },
{ code: 1011, name: ‘뷰티’ },
{ code: 1012, name: ‘출산/유아동’ },
]
request: { code: 0 }

실제 나타나는 결과
* 앞선depth의카테고리목록이마지막으로가져온카테고리목록으로대체됨

Why?
reducer에서 카테고리 계층을 표현하지 않고 상태값을 저장하기 때문

REDUCER 개선
categories: [
{ code: 1010, name: ‘패션/의류잡화’ },
{ code: 1011, name: ‘뷰티’ },
{ code: 1012, name: ‘출산/유아동’ },
]
categories: [
[
{ code: 1010, name: ‘패션/의류잡화’, selected: false },
{ code: 1011, name: ‘뷰티’, selected: false },
{ code: 1012, name: ‘출산/유아동’, selected: true },
],
[
{ code: 2010, name: ‘임신/출산준비할때’, selected: false },
{ code: 2011, name: ‘기저귀갈때’, selected: true },
{ code: 2012, name: ‘분유/유아식품’, selected: false },
],
[ /* .. */ ]
]

import { REQUEST_CATEGORIES, RECEIVE_CATEGORIES } from '../actions/categoryAction'; 
 
categories: [] 
}; 
 
export default function reducer(state = initialState, { type, request, payload }) { 
switch (type) { 
case REQUEST_CATEGORIES: 
return { 
...state, 
isFetching: true 
}; 
case RECEIVE_CATEGORIES: 
const { depth, code } = request; 
const categories = state.categories.slice(0, depth); 
if (depth > 0) { 
categories[depth - 1] = categories[depth - 1].map(o => ({  
code: o.code,  
name: o.name,  
selected: `${o.code}` === `${code}`  
})); 
} 
return { 
...state, 
categories: [...categories, payload], 
isFetching: false 
}; 
default: 
return state; 
} 
} 
categoryReducer.js
REDUCER 개선

VAR VS LET/CONST
* var의문제점 
http://chanlee.github.io/2013/12/10/javascript-variable-scope-and-hoisting
var
함수범위변수를선언및초기화
const
읽기전용상수를선언
let
블록범위지역변수를선언및초기화

VAR VS LET/CONST
var office = 'coupang'; 
var office = 'forward ventures'; // do not error occurred 
console.log(office); // forward ventures 
 
let color = 'blue'; 
let color = 'black'; // TypeError 
 
let count = 0; 
count = 1; 
console.log(count); // 1 
 
const apple = 'apple'; 
apple = 'samsung'; // error 
 
const comic = { name: 'DragonBall', author: ‘Akira Toriyama' }; 
comic = { name: ‘One Piece', author: ‘Oda Eiichiro‘ }; // error 
 
comic.name = ‘One Piece'; 
comic.author = ‘Oda Eiichiro'; 
 
console.log(comic); // name: One Piece, author: Oda Eiichiro 
es6에서는 var 대신 let을 사용하고, 가급적이면 const를 사용하는 것을 추천 
배열이나 객체의 변경도 막겠다면 immutablejs 등을 사용하는 것도 고려

ARROW FUNCTION
// function 
[ 1, 3, 7 ].map(function(value) { 
return value * 2; 
}); 
 
// arrow function 
[ 1, 3, 7 ].map(value => value * 2); 
 
// object를 반환하는 arrow function 
const toMap = name => { 
return { name: name }; 
}; 
 
// object를 반환하는 arrow function 간략 표기 
const toMap = name => ({ name: name });
 
// compare ‘this’ with arrow function and function
 
const object = { 
f1: function() { 
console.log('f1', this); 
function f1_1() { console.log('f1_1', this) } 
setTimeout(f1_1, 1000); 
setTimeout(() => { console.log('f1_2', this) }, 1000); 
}, 
f2: () => { 
console.log('f2', this); 
function f2_1() { console.log('f2_1', this) } 
setTimeout(f2_1, 1000); 
setTimeout(() => { console.log('f2_2', this) }, 1000); 
} 
}; 
object.f1(); // Object, Window, Window 
object.f2(); // Window, Window, Window
arrowfunction에서의this는arrowfunction이정의된지점의this값과같다

DEFAULT PARAMETERS
// 파라미터 기본값이 없는 경우
function increase(number) { 
if (typeof number === 'undefined') return '[ERROR] number is undefined’;
return number + 1; 
}
console.log(increase()); // [ERROR] number is undefined 
console.log(increase(undefined)); // [ERROR] number is undefined 
console.log(increase(10)); // 11 
 
// 파라미터 기본값을 할당한 경우 
function increase(number = 0) { 
return number + 1; 
}
console.log(increase()); // 1 
console.log(increase(undefined)); // 1 
console.log(increase(10)); // 11
OBJECT LITERAL : SHORTHAND
// es5 
var x = 1; 
var y = 2; 
var object = { 
x: x, y: y 
}; 
 
// es6 
const x = 1; 
const x = 2; 
const object = { x, y };

SPREAD SYNTAX
// spread syntax 
 
function myFunction(x, y, z) { 
console.log(`x: ${x}, y: ${y}, z: ${z}`); 
} 
 
const args1 = [ 1, 3, 5 ]; 
const args2 = [ 'foo', 'bar' ]; 
 
myFunction(...args1); // x: 1, y: 3, z: 5 
myFunction(...args2); // x: foo, y: bar, z: undefuned 
 
 
// rest parameters 
 
function restSyntax(x, y, z, ...rest) { 
console.log(`x: ${x}, y: ${y}, z: ${z}, rest: ${rest}`); 
} 
 
restSyntax(...args1); // x: 1, y: 3, z: 5, rest: 
restSyntax(...args1, ...args2); // x: 1, y: 3, z: 5, rest: foo, bar 
restSyntax(9, 8, 7, 6, 5, 4, 3, 2, 1); // x: 9, y: 8, z: 7, rest: 6, 5, 4, 3, 2, 1 
// assign 
 
const arr1 = [ 1, 2 ]; 
const arr2 = [ 4, 5, 6 ]; 
const arr3 = [ ...arr1, 3, ...arr2 ]; 
 
console.log(arr1); // 1, 2 
console.log(arr2); // 4, 5, 6 
console.log(arr3); // 1, 2, 3, 4, 5, 6

DESTRUCTURING ASSIGNMENT : ARRAY
const arr = [ 1, 2, 3, 4, 5, 6 ]; 
 
// assign 
const [ first, second ] = arr; 
console.log(first); // 1 
console.log(second); // 2 
 
// assign with pass some value 
const [ first, , , fourth ] = arr; 
console.log(first, fourth); // 1, 4 
 
// assign rest 
const [ first, second, ...rest ] = arr; 
console.log(first, second); // 1, 2 
console.log(rest); // [ 3, 4, 5, 6 ] 
 
// assign with default value 
const [ x, y = 999 ] = [ 1 ]; 
console.log(x); // 1 
console.log(y); // 999 
 
// nested array 
const [ a, [ b ]] = [ 1, [ 2 ]]; 
console.log(a); // 1 
console.log(b); // 2 
// function 
function myFunction([ x, y, z = 999]) {
console.log(`x: ${x}, y: ${y}, z: ${z}`);
} 
myFunction([ 1, 2, 3 ]); // x: 1, y: 2, z: 3 
myFunction([ 1, 2 ]); // x: 1, y: 2, z: 999 
myFunction(undefined); // Error 
 
// function with default value 
function myFunctionWithDefault([ x, y, z = 999] = []) {
console.log(`x: ${x}, y: ${y}, z: ${z}`);
} 
myFunctionWithDefault(undefined); // x: undefined, y: undefined, z: 999

DESTRUCTURING ASSIGNMENT : OBJECT
// assign
const result = { 
success: false, 
message: ‘exception occurred’, 
callback: () => { console.log('callback function’); } 
};
const { success, message, callback } = result; 
console.log(success); // false 
console.log(message); // 예기치 못한 문제가 발생했습니다. 
console.log(callback()); // callback function 
// nested object
const complex = { 
id: 1, 
detail: { name: ‘Jabi', team: 'Santorini' } 
}; 
const { detail: { name, team } } = complex; 
console.log(name, team); // Jabi, Santorini 
// assign to other name 
const { detail: { name: userName, team: teamName }} = complex; 
console.log(userName, teamName); // Jabi, Santorini 
// function
function myFunction({ id, name, team = 'island' }) { 
console.log(`id: ${id}, name: ${name}, team: ${team}`) 
} 
myFunction({ name: 'Jabi' }); // id: undefined, name: Jabi, team: island 
myFunction(undefined); // Error 
// function with default value 
function myFunctionWithDefault({ id, name, team = 'island' } = {}) { 
console.log(`id: ${id}, name: ${name}, team: ${team}`) 
} 
myFunctionWithDefault(undefined); // // id: undefined, name: undefined, team: island

OBJECT SPREAD / REST SYNTAX (ES7 PROPOSAL STAGE-2)
// in react 
 
export default class Sample extends React.Component { 
render() { 
const props = { 
multiple: true, 
readOnly: true, 
size: 3, 
onClick: this.props.onClick 
}; 
return ( 
<select {...props}> 
<option>option</option> 
</select> 
); 
} 
} 
 
// in redux 
 
function todoApp(state = initialState, action) { 
case SET_VISIBILITY_FILTER: 
return { ...state, visibilityFilter: action.filter } 
default: 
return state 
} 
}

OBJECT.ASSIGN
const o1 = { a: 1 }; 
const o2 = { b: 2 }; 
const o3 = { b: 20, c: 30 }; 
 
const r1 = Object.assign({}, o1, o2); 
const r2 = Object.assign({}, o1, o2, o3); 
const r3 = Object.assign({}, undefined, o2, o3); 
 
console.log(r1); // { a: 1, b: 2 } 
console.log(r2); // { a: 1, b: 20, c: 30 } 
console.log(r3); // { b: 20, c: 30 } 
 
const warning = Object.assign(o1, o2, o3); 
 
console.log(warning); // { a: 1, b: 20, c: 30 } 
console.log(o1); // { a: 1, b: 20, c: 30 }
TEMPLATE STRING
const name = 'Jabi'; 
 
const templateString = `Hello, ${name}. Good to see you.`; 
console.log(templateString); // Hello, Jabi. Good to see you. 
 
const multiline = `first line 
and 
 
last line 
`; 
 
console.log(multiline); 
/* 
fist line 
and 
 
last line 
*/

알아두면 좋을 ES6 문법

알아두면 좋을 ES6 문법
Promise
Set / Map
yield / generator
비동기관련하여자주쓰이므로흐름정도는알아두면좋음
new Set([1,2,3]).has(2), new Map({foo:’bar’}).has(‘foo’)
javascript에 대해 좀 더 파고 싶다면. ( #MDN / Ben Nadel's blog )

자주 쓰지만 안본 ES6/7 문법

뻔한 내용이라…

classes (es6)
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes

classes (es6)
export / import (es6)
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/export 
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import

classes (es6)
설명하려니 내용도 길고 귀차니즘의 압박

classes (es6)
(실은 잘 몰라서)

async / await (es7)
https://jakearchibald.com/2014/es7-async-functions/
classes (es6)
(실은 잘 몰라서)

React, Redux and es6/7

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