SenchaCon 2016: Learn the Top 10 ECMAScript 2015 Features

In this session, Lee will cover the top 10 new features of ECMAScript 2015, their benefits, and go through code examples of how to use them. She will also talk about ECMAScript 2015 compatibilities and incompatibilities with the most widely used browsers today, and how you should plan on developing your applications with ECMAScript 2015.

Transcript

1. Learn the Top 10 best ECMAScript 2015 features Lee Boonstra @ladysign
2. “What you know as JavaScript in browsers and Node.js is actually a superset of ECMAScript. Browsers and Node.js add more functionality through additional objects and methods, but the core of the language remains as defined in ECMAScript."
3. Sit back, and relax
4. Terminology • JavaScript - The language name • ECMAScript - The name of the standard • Transpiler - Transforms ES2015 code to the JavaScript that currently supported in our browsers. • TypeScript - A programming language, which is a superset of JS that aims to align with ES2015, by Microsoft. Compiles to plain JavaScript, because of definition files it can contain type information.
5. 2004: Web 2.0 Advanced Rich Web Applications: Read & Write
6. History
7. About Compatibility You can find an overview of compatibility, in one of these ECMAScript 2015 compatibility tables:http://kangax.github.io/compat-table/es6/ ES2015 Implementations: • V8 (Chrome, Node.js, Opera) • JavaScript Core (Webkit, Safari) • Chakra (MS Edge) • SpiderMonkey (Firefox) • Mobile (iOS 9+, Android 4.4+)
8. Sencha
9. Top 10 ES2015 features 10. Block scoped constructs 9. Default parameters 8. Template Literals 7. Arrow functions 6. Destructuring Assignment 5. For of loop 4. New Methods 3. Promises 2. Classes 1. Modules
10. 10. Block Scoped Constructs
11. What’s hoisting? Variable declarations using var are treated as if they are at the top of the function (or global scope, if declared outside of a function) regardless of where these were placed.
12. Hoisting explained You might have seen something like this before: foo() executes here: (function() { console.log(typeof foo); // prints "function" foo(); // logs "hello sencha" function foo() { console.log("hello sencha!"); } })();
13. Hoisting explained But here it won't... (function() { console.log(typeof foo); // prints "undefined" foo(); // Error: foo is not a function var foo = function() { console.log("hello sencha!"); } })();
14. Hoisting explained This is how the browser interprets it: // prints "undefined" (function() { var foo; console.log(typeof foo); function anon() { console.log("hello sencha!"); } //some anonymous function foo(); // Error: foo is not a function //bind anonymous function to foo foo = anon; })(); Get the code: http://bit.ly/2aAvlpS
15. Block level declarations ECMAScript 2015 defines block-level declarations. With those you can declare variables that are inaccessible outside of a given block scope. Block scopes, also called lexical scopes, are created: 1. Inside of a function 2. Inside of a block (indicated by the { and } characters)
16. Let Declaration The let declaration syntax is almost the same as the syntax for var. (function() { console.log(typeof foo); // ReferenceError: can't access foo(); // I won't even get here. let foo = function() { console.log("hello sencha!"); } })(); Get the code: http://bit.ly/2aAvlpS
17. Can only be declared once in the same scope Below gives a syntax error because you can’t re- declare an identifier within the same (block) scope: var baz = "sencha"; let baz = "extjs"; SyntaxError: redeclaration of non-configurable global property baz
18. Creates new identifier in a new block scope This time it won't throw an error: var baz = "sencha"; if(true){ let baz = "extjs"; //let baz is extjs, but var baz is still sencha } console.log(baz); //logs sencha extjs Note, it doesn’t log , because let baz is only available within its own block scope.
19. Constant declarations You can also define declarations in ES2015 with the const declaration syntax. These values cannot be changed once set. const LIVEURL = "http://www.sencha.com/feed.json";
20. Example of errors The first example is missing initialization. The second example throws a type error because you can’t assign a new variable to a constant. const LIVEURL= "http://www.sencha.com/feed.json"; LIVEURL = "http://www.leeboonstra.com/feed.json"; //TypeError: invalid assignment to const `liveUrl' const LOCALURL; //syntax error, missing = in const declaration
21. This will run perfectly fine It prevents the modification of the binding, not the value itself. const URLS = {}; URLS.LIVE = "http://www.sencha.com/feed.json"; URLS.LIVE = "http://www.leeboonstra.com/feed.json"; URLS.LOCAL = "http://localhost/feed.json"; console.log(URLS); //Object { live: "http://www.leeboonstra.com/feed.json", //local: "http://localhost/feed.json" }
22. Gotcha • var declarations are hoisted to the top of the function scope • Use let for setting declarations in block scopes • Use const for declarations that can’t change the binding • Be careful when you are replacing var for let and const. • let and const can create dead zones • Variables are meant for changing the values! A constant not.
23. 9. Default Parameters
24. About Default Parameters Prior to ECMAScript 2015, code would look like this script. You'll have to pass in the url parameter, but timeout and callback are optional. function makeRequest(url, timeout, callback) { timeout = (typeof timeout !== "undefined") ? timeout : 2000; callback = callback || function() {}; //do something }
25. Default function parameters With ECMAScript 2015, you can actually provide default function parameters: function makeRequest (url, timeout = 2000, callback = function() {} ) { //do something } Get the code: http://bit.ly/2axL0J5
26. Gotcha • Default parameters, can keep your function bodies clean, without re-defining and assigning values to inner variables.
27. 8. Template Literals
28. ES5 JavaScript Strings • JavaScript always lacked, when we are talking about Strings, especially when talking about: - Multiline strings - HTML escaping - Basic string formatting
29. Multiline Strings Example ES5 way of dealing with multiline Strings: var product = "Sencha"; var myText = product + " provides the industry's most " + "comprehensive collection of high-performance, " + "customizable UI widgets.These \"widgets\" include: " + "HTML5 grids, trees, lists, forms, menus, toolbars," + "panels, windows, and much more.";
30. Multiline Strings Here's how it looks in ES2015: let product = "Sencha"; let myText = `${product} provides the industry's most comprehensive collection of high-performance, customizable UI widgets. These "widgets" include HTML5 grids, trees, lists, forms, menus, toolbars, panels, windows, and much more.`; Get the code: http://bit.ly/2azCR78
31. Tagged Templates Template functions, a template tag performs a transformation on the template literal and returns the final string value. function mytag(arrLiterals){ return arrLiterals[0].toUpperCase(); } let message = mytag`hello world!`; //HELLO WORLD! Get the code: http://bit.ly/2aT6eiO
32. Gotcha • `Multiline Strings` FTW! • For easy mixing single and double quotes • String substitution (placeholders in Strings) • Tagged templates are like template functions in JS.
33. 7. Arrow Functions
35. Arrow Functions Arrow functions, are a new syntax for functions, defined with an arrow. Consider the following ES5 functions: var calculate = function(x,y){ return x + y; } var sayHello = function(name){ return "Hello " + name; } calculate(5,10); //returns: 15 sayHello('Lee'); //returns: Hello Lee
36. Arrow Functions And compare these to the following new syntax: let calculate = (x,y) => { return x + y; } let sayHello = (name) => { return "Hello " + name; } calculate(5,10); //returns: 15 sayHello('Lee'); //returns: Hello Lee
37. Arrow Functions This would work as well: let calculate = (x,y) => x + y; let sayHello = (name) => "Hello " + name; Get the code: http://bit.ly/2b7G8Gz
38. Be aware Arrow functions could slightly behave different compared to traditional JavaScript functions: • No this, super, arguments • No duplicated named arguments • Can not be called with new • No prototype • You can’t change this • Lexical this
39. No object You must rely on named and rest parameters to access function arguments... arguments //ES5 var foo = function (x,y) { return arguments[0]; } foo("lee", "2"); //returns "lee"; //ES2015 var foo = (x,y) => arguments[0]; foo("lee","2") //ReferenceError: arguments is not defined [Learn More] Get the code: http://bit.ly/2aNnt3z
40. No duplicate named args Not in strict or nonstrict mode, as opposed to non- arrow functions that cannot have duplicate named arguments only in strict mode. //ES5 var x = function (x,x) { return x; } x("hello", "world"); //returns "world"; //ES2015 var x = (x,x) => x; //SyntaxError: duplicate argument names not //allowed in this context Get the code http://bit.ly/2aNnt3z
41. Cannot be called with • Arrow functions do not have a [[Construct]] method and therefore cannot be used as constructors. • Arrow functions throw an error when used with new. new var x = (x) => x; new x(); //TypeError: x is not a constructor
42. No prototype • Since you can’t use on an arrow function, Since you can’t use new on an arrow function, there’s no need for a prototype. • The prototype property of an arrow function doesn’t exist. var x = (x) => x; x.prototype.foo = "foo"; //TypeError: x.prototype is undefined
43. Lexical Remember var me = this; or var self = this; ? Often used when working with callbacks, to refer to the original scope, while the current scope changed, because of a callback. this function VideoGame(){ //ES5 var me = this; me.title = "Uncharted", me.version = 3; setInterval(function() { return me.title + " " + me.version++; console.log("1:", this); //Context is Window console.log("2:", me); //Context is VideoGame() }, 5000); }
44. Lexical • An arrow function does not create it's own this scope, rather it captures the this value of the enclosing scope. function VideoGame(){ this.title = “Uncharted”; this.version = 3; setInterval(() => { console.log(this.title + " " + this.version++); // |this| properly refers to the VideoGame object }, 5000); } Get the code: http://bit.ly/2azNHae this
45. Gotcha • Arrow functions =>, write less code • Ideal for callback function / inline functions. • When working in teams, make sure everyone understands. • Be aware: • No arguments • Can not create instance with new • No prototype • Lexical this I’ve created examples for this, which I will leave in the slidedeck.
46. 6. Destructuring Assignment
47. Consider this Object var myobject = { name: "Sencha", logo: { small: { png: 'http://path/to/small.png', jpg: 'http://path/to/small.jpg' }, large: { png: 'http://path/to/large.png', jpg: 'http://path/to/large.jpg' } } }
48. ES5: Working with Objects In ES5 you would do something like this: var logo = myobject.logo.small.png; var small = myobject.logo.small; var company = myobject.name; console.log(logo); //Sencha console.log(small); // { png: "http://path/to/small.png", //jpg: "http://path/to/small.jpg" } console.log(company); //http://path/to/small.jpg
49. ES2015: Object Destructuring Compare this to the ES2015 way, with object destructuring: let { name, logo : { small : { jpg } } } = myobject; console.log(name); //Sencha console.log(small); // { png: "http://path/to/small.png", //jpg: "http://path/to/small.jpg" } console.log(jpg); //http://path/to/small.jpg Get the code: http://bit.ly/2aDgsmT
50. ES5: Working with Arrays Before you would often fetch information from objects or arrays, that could lead in lots of code which looks the same, just to get certain data in local variables. var myarray = ["Ext JS", "GXT", "Sencha Test"]; var myvar1 = myarray[0]; var myvar2 = myarray[1]; var myvar3 = myarray[2]; console.log(myvar1, myvar2, myvar3) //Ext JS GXT Sencha Test
51. ES2015: Array Destructuring You can also destruct arrays: let myarray = ["Ext JS", "GXT", "Sencha Test"]; let [myvar1, myvar2, myvar3] = myarray; console.log(myvar1, myvar2, myvar3) //Ext JS GXT Sencha Test Get the code: http://bit.ly/2aA099W
52. Gotcha • Extract data from Arrays and Objects • Ideal for when working with deeply nested Objects. No longer you need to create extra variables with dot-notation.
53. 5. for..of loop
54. ES5: For loops ES5 has various ways to loop through array elements and objects. • ES5 for loop • ES5 forEach() loop, can’t break, continue and return • ES5 for in, iterates through object properties var array = ["a", "b", "c"]; Var obj = { firstname: "Lee", lastname: "Boonstra" }; //1) for (var i = 0; i < array.length; i++) { console.log(array[i]); } //2) array.forEach(function(element) { console.log(element); }); //3) for(prop in obj) { console.log(prop + " = " + obj[prop]); }
55. For of loop New in ES2015, the for...of statement creates a loop iterating over iterable objects (including Array, Map, Set, String, arguments object etc…) var array = ["a","b","c","d"]; for(i of array){ console.log(i); if(i == "c") return; }
56. Gotcha • ES6 For of loop, most concise, direct syntax yet for looping through array elements • ..but, the old-fashioned ES5 for loop just performs better • https://www.incredible-web.com/blog/performance-of-for-loops-with-javascript/
57. About For..of performance • https://www.incredible-web.com/blog/performance-of-for-loops-with-javascript/
58. 4. New methods
59. ES5: Check equality console.log(5 == 5); // true console.log(5 == "5"); // true console.log(5 === 5); // true console.log(5 === "5"); // false console.log(+0 == -0); // true <----------WAIT WHAT?!! console.log(+0 === -0); // true <---------WAIT WHAT?!! console.log(NaN == NaN); // false <--------WAIT WHAT?!!
60. ES2015: Object.is() This method performs strict equality on any value, effectively becoming a safer version of === when dealing with special JavaScript values: console.log(Object.is(5, 5)); // true console.log(Object.is(5, "5")); // false console.log(Object.is(+0, -0)); // false <---- Oh, OK! console.log(Object.is(NaN, NaN)); // true <--- Oh, OK! Get the code: http://bit.ly/2b8o9AB
61. ES5: Mixin Pattern (1) Consider this piece of code: function Observable() { //... } Observable.prototype = { constructor: EventTarget, on: function() { console.log("An event happened.") } } //the receiver object var AnotherObject = {}
62. ES5: Mixin Pattern (2) The mixin() function iterates over the own properties of supplier and copies them onto the receiver. function mixin(receiver, supplier) { Object.keys(supplier).forEach(function(key) { receiver[key] = supplier[key]; }); return receiver; } mixin(AnotherObject, Observable.prototype); AnotherObject.on("customevent"); //An event happened.
63. ES2015: Object.assign() This method makes it easier to change multiple properties on a single object at once. function Observable() { } Observable.prototype = { constructor: EventTarget, on: function() { console.log("An event happened.") } } let SomeObject = {} Object.assign(SomeObject, Observable.prototype); SomeObject.on("customevent"); //An event happened. Get the code: http://bit.ly/2b2KB0E
64. Object.setPrototypeOf() (1) • The Object.setPrototypeOf() method makes it possible to modify. var MySong = { sing() { return "Girl, you know it's true..."; } }; var MilliVanilli = { dance() { return "Dance!"; } }; var Numarx = Object.create(MySong); Numarx.sing(); // "Girl, you know it's true..." Object.getPrototypeOf(Numarx) === MySong; //true //MilliVanilli takes over the Numarx prototype: Object.setPrototypeOf(MilliVanilli, Numarx); MilliVanilli.sing(); // "Girl, you know it's true..." MilliVanilli.dance(); //Dance! Object.getPrototypeOf(MilliVanilli) === Numarx; //true
65. Object.setPrototypeOf() - super (2) • Finally, you can use the super keyword to call methods on an object’s prototype. The this binding inside a method invoked using super is setup automatically to work with the current value of this. var MilliVanilli = { sing(){ return super.sing() + " Oeh Oeh Oeh"; } }; var Numarx = Object.create(MySong); Numarx.sing(); // "Girl, you know it's true..." //take over the Numarx prototype, but overrides the sing(): Object.setPrototypeOf(MilliVanilli, Numarx); MilliVanilli.sing(); // "Girl, you know it's true... Oeh Oeh Oe Get the code: http://bit.ly/2auVcAQ
66. ES5: Find in Array Find in an array of numbers which number is the closest, and never go under the given number: var numbers = [0,5,10,15,20,25]; function closest(arr, n){ var x = Math.max.apply(null, arr); for(var i = 0; i < arr.length; i++){ // Check if it is higher than your number // but lower than your closest value if(arr[i] >= n && arr[i] < x) x = arr[i]; } return x; } closest(numbers, 6); //10
67. ES2015: Array.find() Find in an array of numbers which number is the closest, and never go under the given number: let numbers = [0,5,10,15,20,25]; numbers.find(n => n > 6) //10 Get the code: http://bit.ly/2b8Xi9x
68. More New Methods There are much more new methods available in ES2015. New methods on the following prototypes: • Object • Array • Number • Math
69. Gotcha • Object.is() – Equality checking, the right way • Object.asign() – Ideal for coding Mixin patterns • More new methods on prototypes of: • Object - http://bit.ly/2cbFU3l • Array - http://bit.ly/2co0yNn • Number & Math - http://bit.ly/2cnDRb0
70. 3. Promises
71. Async JavaScript Promises are new to ECMAScript 2015, and helps you with dealing with asynchronous code. JavaScript code is single threaded: • Code executes from top to bottom • Right after each other • 2 bits of code cannot run at the same time
72. Event Loop • The Event Loop is a queue of callback functions. When the JS engine sees an async method, that method is pushed into the queue.
74. ES5: Callbacks //Node.js Example var done = function(err, jobs){ res.render("myview", { user : req.user, jobs: jobs }); }; getJobs = function(req, done){ // Something asynchronous: MongoDB, // request jobs from a database Job.findJobsOfUser(req.user._id, function(err, jobs){ if(err) throw err; done(null, jobs); }); } var jobs = getJobs(req, done);
75. ES2015: Promises (1) getJobs(req).then(function(jobs){ if(jobs){ //now if I want to chain this with more calls //i just run the res.render finally res.render("profile", { user: req.user, jobs: jobs }); } }, function(error){ throw error; });
76. ES2015: Promises (2) function getJobs(req){ var promise = new Promise(function (resolve, reject) { //Something asynchronous: MongoDB, //request jobs from a database Job.findJobsOfUser(req.user._id, function (err, jobs) { if (err) reject(err); //reject the promise else resolve(jobs); //or resolve the promise }); }); return promise; } The advantage of this piece of code, is that it’s better readable and maintainable. Get the code: http://bit.ly/2b91GW9
77. Gotcha • When you deal with callbacks, (async ), you pass a function in a function and you deal with success and failure. • The result of an async task (promise) can be fulfilled or rejected. It makes async JS better readable. • Promises are chainable.
78. 2. Classes
80. Just Syntactical Sugar The class syntax is not introducing a new object-oriented inheritance model to JavaScript. They mainly provide more convenient syntax to create old- school constructor functions.
81. ES5: Class-like definition var Character = function (name, type, universe) { this.name = name; this.type = type; this.universe = universe; }; Character.prototype.introduce = function () { return "I am " + this.name + ". A " + this.type + " from " + this.universe + "."; }; var batman = new Character("Batman", "superhero", "DC"); batman.introduce(); //I am Batman. A superhero from DC.
82. ES2015: Class-like definition class Character { constructor(name, type, universe){ this.name = name; this.type = type; this.universe = universe; } introduce() { return "I am " + this.name + ". A " + this.type + " from " + this.universe + "."; } } typeof Character; //"function" let batman = new Character("Batman", "superhero", "DC"); batman.introduce(); //I am Batman. A superhero from DC.
83. Getters & Setters class SuperHero { constructor(name, ability){ this._name = name; this._ability = ability; } setName(name){ this._name= name; } getName(){ return this._name; } setAbility(ability){ this._ability = ability; } getAbility(){ return this._ability; } } Get the code: http://bit.ly/2aAdgL4
84. Getters & Setters var spiderman = new SuperHero(); spiderman.setName("Spiderman"); spiderman.setAbility("Shoot SpiderWebs"); console.log(spiderman.getName()); //"Spiderman" console.log(spiderman.getAbility()); //Shoot SpiderWebs Get the code: http://bit.ly/2aAdgL4
85. ES5: Class Inheritance (1) var Character = function (name, type, universe) { this.name = name; this.type = type; this.universe = universe; }; Character.prototype.introduce = function () { return "I am " + this.name + ". A " + this.type + " from " + this.universe + "."; };
86. ES5: Class Inheritance (2) var Wookiee = function (name) { Character.call(this); this.name = name; this.type = "Wookiee"; this.universe = "Star Wars"; }; Wookiee.prototype = Object.create(Character.prototype); Wookiee.prototype.constructor = Wookiee; Wookiee.prototype.talk = function(){ var roar = "Uughguughhhghghghhhgh raaaaaahhgh" if(this.name == "Chewbacca") roar = roar + " Millennium Falcon"; return roar; }
87. ES5: Class Inheritance (3) var chewbacca = new Wookiee("Chewbacca"); chewbacca.introduce(); //I am Chewbacca. A wookiee from Star Wars. chewbacca.talk(); //Uughguughhhghghghhhgh raaaaaahhgh Millennium Falcon var chief = new Wookiee("Chief"); chief.introduce(); //I am Chief. A wookiee from Star Wars. chief.talk(); //Uughguughhhghghghhhgh raaaaaahhgh
88. ES2015: Class inheritance (1) class Character { constructor(name, type, universe){ this.name = name; this.type = type; this.universe = universe; } introduce() { return "I am " + this.name + ". A " + this.type + " from " + this.universe + "."; } };
89. ES2015: Class inheritance (2) class Wookiee extends Character { constructor(name){ super(); this.name = name; this.type = "Wookiee"; this.universe = "Star Wars"; } talk(){ var roar = "Uughguughhhghghghhhgh raaaaaahhgh" if(this.name == "Chewbacca") roar = roar + " Millennium Falcon"; return roar; } };
90. ES2015: Class inheritance (3) var chewbacca = new Wookiee("Chewbacca"); chewbacca.introduce(); //I am Chewbacca. A wookiee from Star Wars. chewbacca.talk(); //Uughguughhhghghghhhgh raaaaaahhgh Millenium Falcon var chief = new Wookiee("Chief"); chief.introduce(); //I am Chief. A wookiee from Star Wars. chief.talk(); //Uughguughhhghghghhhgh raaaaaahhgh
91. Static Methods Static methods are methods which can be accessed as classname.methodName() instead of classInstanceName.methodName().
92. ES2015: Static Method (1) class SuperHero { constructor(name, ability){ this._name = name; this._ability = ability; } setAbility(name){ this._ability = name; } getAbility(){ return this._ability;} .. static getMarvelFact() { return "Marvel Comics is the common name and" + " primary imprint of Marvel Worldwide Inc."; } }
93. ES2015: Static Method (2) //Create an object var spiderman = new SuperHero(); spiderman.setName("Spiderman"); spiderman.getMarvelFact(); //TypeError: spiderman.getMarvelFact is not a function //Static Method from ClassName SuperHero.getMarvelFact(); //Marvel Comics is... Get the code: http://bit.ly/2arntnv
94. Gotcha • ES2015 classes, syntactical sugar, the type is a function under the hood • Class syntax • Inheritance: ES2015 classes can extend classes • Static Classes
95. 1. Modules
96. ES2015: Modules Other languages have packages Before ES2015, JavaScript shared only one global scope which can cause collisions and security problems. ES2015 Goal: solve the scope problem: No module code executes until requested modules are available and processed.
97. Modules are JavaScript files that are loaded in a different mode, than scripts. Here are some differences: 1. Module code automatically runs in strict mode, you can’t opt-out. 2. Variables created in the top level of a module aren’t automatically added to the shared global scope. It only exist in the module. 3. The value of this in the top level of a module is undefined. 4. Modules must export anything that should be available to code outside of the module. 5. Modules may import bindings from other modules.
98. Example Module (1) libs/leftpad.js function leftPadFunction (str, len, ch) { str = String(str); var i = -1; if (!ch && ch !== 0) ch = ' '; len = len - str.length; while (++i < len) { str = ch + str; } return str; } //export leftPadFunction; module.export { leftpad: leftPadFunction }
99. Example Module (2) app.js //import * as leftpad from '../leftpad-module'; import leftpad from '../leftpad-module'; leftpad("lee", 5, "-") //"--lee" leftpad("9", 3, "0") //"009" Get the code: http://bit.ly/2aH4QPc
100. Gotcha • ES2015 answer to packages • Fix global scope problem (collisions) • Modules run in a different mode than script • this in top level of the module equals undefined • Modules must export anything that should be available to code outside of the module.
101. More ECMAScript 2015
102. More ECMAScript 2015 There are more nice ECMAScript 2015 features which didn’t fit in my presentation top 10: • Spread Operator • Maps, Weakmaps, Sets & Weaksets • Generators • … See also: http://bit.ly/2clUmIy
103. ES2015 & Sencha
104. Sencha
105. Not all ES2015 features are new to Ext devs Some of these new ES2015 features already exist for years in Ext JS, and they are more advanced. ES2015 Tagged Template Templates Ext Ext.XTemplate Object.is() Ext.Object.equals() Object.assign() Ext.apply() Promises Ext.Promise Classes Ext.Base Modules Ext.Loader
106. There’s ES2015 support in Sencha Cmd 6.5 • This will require tooling. Our frameworks have to deal with legacy browsers. • Sencha will need a transpiler to compile back to old fashioned ES5 code. • Our goal is to let your ES2015 code run together with the Sencha framework code. • Cmd is Java based! With Sencha Cmd 6.5, code gets transpiled! Under the hood, we will use Google Closure Compiler. (We replaced Rhino)
107. Be aware of the transpiler! • If you need to use it, you owe yourself to check the output and end result • Transpilers generate code which is supported by the current browsers. It might not be the code what you would expected.
108. ES2015 support in the next major Ext JS version • Next Ext JS version will make changes in the class system Ext.Base • Write ES2015 “class” syntax to extend from Sencha classes • New tooling, Node.js / NPM based with integration of Babel. Will allow TypeScript support.
109. • http://speakerdeck.com/savelee • http://www.leeboonstra.com • http://es6-features.org/#RawStringAccess • https://github.com/getify/You-Dont-Know- JS/blob/master/es6 & beyond/README.md#you- dont-know-js-es6--beyond • https://leanpub.com/understandinges6 • https://developers.google.com/closure/compiler • https://github.com/google/closure-compiler/wiki/ECMAScript6 • https://kpdecker.github.io/six-speed/ Resources