What's happening in frontend now?

by koba04

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What's happening in frontend now? YAPC::Asia 2015 (8/21) @koba04

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koba04 • Toru Kobayashi • Web application engineer • ≠ Frontend engineer • Single Page Application • Backbone -> Angular -> React

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Agenda • Ajax ʙ • Language • Web Application • Tools • Environment

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2005 2015 Ajax ECMAScript 5 ECMAScript 2015

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Once upon a time…

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Good old web • Client requests HTML. • Server responses HTML. • Very simple • JavaScript doesn’t have to use. browser server GET /index.html index.html GET /about.html about.html

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Ajax! • Google Map • Asynchronous updates • We need JavaScript! • From Page to Application

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We need to write JavaScript…

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Language

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ECMAScript 5

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ECMAScript 5 (5.1) • “use strict”; • Object.create, Object.deﬁneProperty • Array.prototype.(forEach, map, ﬁlter, reduce…) • JSON.parse, JSON.stringify • IE9ʙ 2009 2011(5.1)

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CoffeeScript

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CoffeeScript • Jeremy Ashkenas • CoffeeScript is a little language that compiles into JavaScript • Brevity and readability. • Rails 3.1 CoffeeScript • Some features are in ECMAScript 2015 2010(1.0)

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class Parent class Hello extends Parent constructor: (@name) -> super() method: -> console.log @name hello = new Hello 'coffee' setTimeout( () => hello.method(), 1000 )

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Web Application

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jQuery

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jQuery • John Resig • DOM API is too low level • Browsers compatibility • jQuery Plugin • document.querySelector, Deferred(Promise)… 2006

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$button.on(‘click’, function() { $.ajax( method: ‘GET’, url: ‘/api/item_list’ ) .done(function(items) { $ul = $(‘

’); $.each(items, function(index, value) { $ul.append($(‘

’ + value + ‘

’)); }); $(‘.items’).append($ul); }); }); });

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Backbone.js

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Backbone.js • Jeremy Ashkenas • JavaScript MVC framework • Observer pattern • Depend on jQuery & underscore.js 2010

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Backbone.Collection Backbone.View Backbone.Model Backbone.Model Backbone.Router Backbone.Event Backbone.History

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var View = Backbone.View.extend({ events: { 'change .text': 'change' }, initialize: function() { this.listenTo(this.model, 'change', this.render); }, change: function() { this.model.set('text', this.$el.find('.text').val()); }, render: function() { this.$el.html( '

' + this.model.get('text') + ‘

' ); return this; } }); $('#app').append( new View({ model: new Backbone.Model({text: ‘initial'}) }).render().$el );

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Tools

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Node.js

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Node.js • Node.js is a platform built on V8 • npm (173,476 packages) • server & cli • Event loop is that it runs under a single thread • Stream 2009

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Grunt

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Grunt.js • The JavaScript Task Runner • Not a build tool • Conﬁgurable • Yeomanɺassemble • Last release is 2014 May… • npm scripts 2012

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CoffeeScript Port JavaScript watch JavaScript Running Webserver Minified JavaScript Output files Src files compile uglify exec

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module.exports = (grunt) -> watch: coffee: files: ["coffee/**/*.coffee"] tasks: ["js"] coffee: files: "static/js/app.js": [ "coffee/app.coffee" "coffee/model/*.coffee" "coffee/collection/*.coffee" "coffee/view/*.coffee" ] concat: dev: src: [ "bower_components/jquery/jquery.js" "bower_components/underscore/underscore.js" "bower_components/backbone/backbone.js" "static/js/app.js" ] dest: “static/js/all.js"

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Environment

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Chrome

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Chrome • Fast! Fast! Fast! • Webkit (version 28ʙ Blink) • Google V8 JavaScript Engine • JavaScriptCore(Safari), Chakra(IE), SpiderMonkey(Firefox) • Just in Time (JIT) 2008

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Single Page Application

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Language

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TypeScript

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TypeScript • Microsoft • Typed superset of JavaScript • Class, Interface, Generics, Modules… • IDE Support • DeﬁnitelyTyped 2012

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class Greeter { greeting: string; constructor(message: string) { this.greeting = message; } greet(): string { return "Hello, " + this.greeting; } } var greeter = new Greeter("world");

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AST

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AST • Abstract Syntax Tree • SpiderMonkey Parser API • https://developer.mozilla.org/en-US/docs/ Mozilla/Projects/SpiderMonkey/Parser_API • Esprima, Espree, Acorn, Babylon • ESTree, ShiftAST

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var answer = hoge * 7; VariableDeclarator Identiﬁer answer Identiﬁer hoge BinaryExpression * Literal 7

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{ "type": "Program", "body": [ { "type": "VariableDeclaration", "declarations": [ { "type": "VariableDeclarator", "id": { "type": "Identiﬁer", "name": "answer" }, "init": { "type": "BinaryExpression", "operator": "*", "left": { "type": "Identiﬁer", "name": "hoge" }, "right": { "type": "Literal", "value": 7, "raw": "7" } } } ], "kind": "var" } ] } var answer = hoge * 7; Parse by Esprima http://esprima.org/demo/parse.html

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Your JavaScript Espree Acorn … AST Transpile Lint Analyze

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Libraries using AST • Linter - ESLint • Analyzer - istanbul, plato • Test - power-assert • Transpiler - browserify, babel

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Web Application

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https://blog.twitter.com/2012/improving-performance-on-twittercom

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Problems of SPA • SEO • Performance(initial load) • Maintenance browser server HTML JavaScript JSON Data

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Isomorphic (Universal JavaScript)

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Isomorphic • Share the code between client and server • → For maintenance • Initial render executes on the server • → For SEO and Performance • Frameworks have different approaches • Meteor, Rendr…

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browser server HTML included contents GET app.js GET / Node.js You can see the contents! Start to run your JavaScript on the browser GET /other/page Route on the browser

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The requirements of SPA • Binding JSON data to DOM • Routing by the browser History API • Browser side template engine • Data management • Memory management

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Angular.js

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Angular.js • Google • HTML enhanced for web apps. • 2way Data binding • Full stack (ng-http, ng-router…) • Very simple? (initially) • Angular 2 is completely different. release:2009 1.0: 2012

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Tools

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SPA is… • Many assets ﬁles • JavaScript, CSS, template… • Hard to manage concatenating with Grunt • Increase a build time…

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gulp

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gulp • Stream base build system • Simple tasks pipe as stream • Programmable not conﬁgurable • Simple API • task, run, watch, src, dest 2014

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CoffeeScript Stream pipe Src ﬁles Stream pipe gulp.src coffee Stream pipe Stream pipe gulp.dest Files dest ﬁles

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var gulp = require('gulp'); var concat = require(‘gulp-concat'); var coffee = require('gulp-coffee'); var uglify = require('gulp-uglify'); var coffeeFiles = './src/**/*.coffee'; gulp.task('compile', function(){ gulp.src(coffeeFiles) ��.pipe(coffee()) .pipe(concat(‘app.js’)) .pipe(uglify()) .pipe(gulp.dest(‘dist’)); }); gulp.task(‘watch’, function() { gulp.watch(coffeeFiles, ['compile']); });

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browserify

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browserify • substack • Browserify lets you require('modules') in the browser by bundling up all of your dependencies. • No more concatenating which is depending on the order • It makes possible to share code between the browser and server. 2013

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require(‘./foo’); require(‘./bar’); bundle.js app.js require(‘events’); require(‘react’); … … bar.js foo.js events react

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StatelessɾComposableɾ Stream

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Language

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ECMAScript 2015

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ECMAScript 2015 • ECMAScript 6 • JavaScript is more powerful. • Class, Modules, Arrow Function, Promise… • Destructuring assignment — • Browsers haven’t supported all features yet. 2015 June

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http://kangax.github.io/compat-table/es6/

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class Person { method(val=“default”) { console.log(val); } method2(...array) { return new Promise((resolve, reject) => { setTimeout(() => { resolve(array.map(val => val * 2)); }, 1000); }); } } const person = new Person(); person.method2(1, 2, 3).then(array => console.log(array)); // [2, 4, 6] const user = {name: ‘Jim’, age: 20}; const {name, age} = user;

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Babel

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Babel • Sebastian McKenzie • JavaScript transpiler • Use next generation JavaScript, today. • We can use ECMAScript 2015 now! • Stage option (default is stage2) ʙ 5.x 2014

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TC39 • Technical Committee 39 • proposals into 4 stages • Stage 0 - Strawman • Stage 1 - Proposal • Stage 2 - Draft • Stage 3 - Candidate • Stage 4 - Finished

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https://github.com/tc39/ecma262

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Environment

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Service Workers

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Service Workers • JavaScript is more powerful. • Run independently of web pages. • Intercept Request • Ofﬂine / Cache • Background Sync • Push Notiﬁcation • HTTPS Only

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// index.js if ('serviceWorker' in navigator) { navigator.serviceWorker.register('sw.js').then( sw => console.log('success'), err => console.log('error', err) ); } // sw.js self.addEventListener('install', sw => console.log('oninstall')); self.addEventListener('fetch', ev => { if (ev.request.url.indexOf('test') !== -1) { ev.respondWith(new Response('Hello Service Worker')); } });

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Extensible Web

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Extensible Web • The Extensible Web Manifesto • https://extensiblewebmanifesto.org/ • New low-level capabilities • Virtuous cycle • Prioritize efforts • Web Components ➜ Polymer

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Web Application

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React.js

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React.js • Facebook • Stateless Component • Mutability ➜ Complexity • Declarative programming • VIRTUAL DOM • Isomorphic! 2014

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ᶃ USJHHFS BOFWFOU ᶄFWFOU ᶅVQEBUFBTUBUF ᶆQBTTFTBTUBUFBTQSPQT ᶇVQEBUF%0. CZQSPQT Stateful Stateless

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class App extends React.Component { constructor(...args) { super(args); this.state = {count: 0}; } onClick() { this.setState({count: this.state.count + 1}); } render() { const {count} = this.state; return (

{count}

click

); } } React.render(, document.getElementById(‘app’));

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Flux

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Flux • Facebook • An application Architecture for Building User Interfaces • Unidirectional data ﬂow

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Function Reactive Programming

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Functional Reactive Programming • Asynchronous data streams • A stream is a sequence of ongoing events ordered in time. • Mouse event, touch event, fetch response… • Observer and observable • Rx.js, Bacon.js, ECMAScript Observable(stage1)

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const $ = document.querySelector.bind(document); const plus = Rx.Observable.fromEvent($('#plus'), 'click'); const minus = Rx.Observable.fromEvent($('#minus'), 'click'); plus .map(1) .merge(minus.map(-1)) .scan((acc, value) => acc + value) .subscribe(value => sum.textContent = value) ;

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click plus click minus click minus click plus click plus plus.map(1) minus.map(-1) scan((acc, value) => acc + value) -1 1 -1 1 1 1 0 -1 0 1

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Redux

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Redux • Inspired by Flux and Elm • Actions, A Store, Reducers • Reducers are pure functions • (state, action) => state • State is read-only • Single source of truth

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Reducer Component Reducer Component Store messages: [‘hello’] filter: ALL type: ADD_MESSAGE text: ‘hoge’ messages => messages.concat(action.text) filter => action.filter Action type: FILTER text: UNREAD Action Reduce Reduce subscribe

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

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Conclusion

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Combination simple parts

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Unix philosophy • Small is beautiful. • Make each program do one thing well. • Build a prototype as soon as possible. • Choose portability over efficiency. • Store data in flat text files. • Use software leverage to your advantage. • Use shell scripts to increase leverage and portability. • Avoid captive user interfaces. • Make every program a Filter.