Codelicious: Intro to ES2015

2. @Jack_Franklin
3. @pusher
4. ES2015: finished!
5. https://kangax.github.io/compat-table/es6/
6. It’s happening! • Edge 14: 90% • Chrome 52 / Opera 39: 98% • FF 49: 93% • Safari 10: 100% • Node 6: 93%
7. Arrow Functions
8. 1 [1, 2, 3].map(function(numbers) { 2 return numbers * 2; 3 }); 4 5 [1, 2, 3].map(numbers => numbers * 2);
9. undefined 'Tom' undefined 'Zoe' 1 var person = { 2 name: 'Jack', 3 friends: ['Tom', 'Zoe'], 4 logFriends: function() { 5 this.friends.forEach(function(f) { 6 console.log(this.name, f); 7 }); 8 } 9 }
10. 'Jack' 'Tom' 'Jack' 'Zoe' 1 var person = { 2 name: 'Jack', 3 friends: ['Tom', 'Zoe'], 4 logFriends: function() { 5 this.friends.forEach(f => { 6 console.log(this.name, f); 7 }); 8 } 9 }
11. Object Literals
12. 1 var literal = { 2 foo: function() {...}, 3 bar() {...} 4 }
13. 1 var newKey = 'foo'; 2 var newObj = {}; 3 newObj[newKey] = true; 4 5 var otherNewObj = { 6 [newKey]: true 7 };
14. Template Strings
15. 1 var str = '2 + 2 is: ' + (2 + 2); 2 3 var otherStr = `2 + 2 is: ${2 + 2}`;
16. 1 var str = `they can 2 span multiple 3 4 lines and stuff 5 `;
17. Destructuring
18. 1 var array = [1, 2, 3]; 2 3 var [first, ...rest] = array; 4 5 first // 1 6 rest // [2, 3]
19. 1 var person = { 2 name: 'Jack', 3 age: 24 4 }; 5 6 var { name, age } = person; 7 8 name // 'Jack' 9 age // 24
20. 1 var getTweetInfo = function() {...}; 2 3 var { text, user } = getTweetInfo();
21. 1 var person = { 2 name: { 3 first: 'Jack', 4 last: 'Franklin' 5 } 6 }; 7 8 var { name: { first } } = person; 9 10 first // 'Jack';
22. 1 var person = { 2 name: { 3 first: 'Jack', 4 last: 'Franklin' 5 } 6 }; 7 8 var { name: { first: foo } } = person; 9 10 foo // 'Jack' 11 first // ReferenceError
23. The rest/spread/splat operator
24. 1 var numbers = [1, 2, 3] 2 var moreNumbers = [...numbers, 4, 5]; 3 // moreNumbers [1, 2, 3, 4, 5]
25. Function Arguments
26. 1 function foo(x = 1) { 2 return x; 3 } 4 5 foo() // 1 6 foo(2) // 2
27. 1 function foo(...args) { 2 log('got args', args); 3 } 4 5 function bar() {...}; 6 7 var args = [1, 2, 3]; 8 bar.apply(this, args); 9 bar(...args);
28. 1 function foo(obj) { 2 return obj.x + obj.y; 3 }; 4 5 function foo({ x, y }) { 6 return x + y; 7 }
29. Classes
30. 1 class Person { 2 constructor(name) { 3 this.name = name; 4 } 5 6 fullName() { 7 return `Name is ${this.name}`; 8 } 9 } 10 11 var jack = new Person('Jack'); 12 jack.fullName();
31. Modules
32. 1 // foo.js 2 export default function() { 3 return 2; 4 } 5 6 //main.js 7 import foo from './foo'; 8 foo(); // 2
33. 1 // foo.js 2 function foo() { 3 return 2; 4 } 5 6 export { foo }; 7 8 // main.js 9 import { foo } from './foo'; 10 foo(); // 2
34. each module has its own scope
35. static imports and exports
36. tree shaking
37. 1 // some 3rd party library 2 export function merge() {...}; 3 export function filter() {...}; 4 export function map() {...}; 5 6 // your app 7 8 import { filter } from 'third-party';
38. 1 // final bundle 2 function filter() {...}; 3 ...your app code...
39. const and let
40. scope
41. window (global) scope function scope
42. foo = 2 bar = 3 x = fn baz = 4 1 var foo = 2; 2 3 function x() { 4 bar = 3; 5 var baz = 4; 6 }
43. x foo = 1 bar = 2 1 function x() { 2 var bar = 2; 3 if (...) { 4 var foo = 1; 5 } 6 }
44. window (global) scope function scope block scope let const
45. x bar = 2 foo = 1 baz = 3 1 function x() { 2 var bar = 2; 3 if (...) { 4 let foo = 1; 5 const baz = 3; 6 } 7 }
46. never var, always let
47. and maybe even const
48. 1 const x = 2; 2 x = 3; // NOPE! 3 4 const y = { a: 1 }; 5 y = { b: 1 }; // NOPE! 6 7 y.a = 2; //...yeah 8 delete y.a; //...yeah 9 y.b = 3; //...yeah
49. so much more! sets, maps, proxies, symbols, generators, new object APIs
50. Never again
51. ES2016 ** operator Array.prototype.includes
52. Thanks! @Jack_Franklin