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@sayar
Last active Aug 29, 2015
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FITC - What's New in ES6 for Web Devs - Sample code from my presentation
'use strict';
// app.js
import * as math from "math";
alert("2π = " + math.add(math.pi, math.pi));
'use strict';
// Sample Code from FITC Presentation: "What's New in ES6 for Web Devs"
// Function Scoping Sample 1
function scope1() {
var foo = 'FITC';
console.log(foo); // Prints 'FITC'
if (true) {
var foo = 'BAR';
console.log(foo); // Prints 'BAR'
}
console.log(foo); // Prints 'BAR'
}
// Function Scoping Sample 2
function scope2() {
var foo;
foo = 'FITC';
console.log(foo); // Prints 'FITC'
if(true) {
foo = 'BAR';
console.log(foo); // Prints 'BAR'
}
console.log(foo); // Prints 'BAR'
}
// Function Scoping Sample 3 - Hoisting
function scope3() {
var foo = 'FITC';
if(!bar) {
console.log(foo + ' ' + bar);
// Prints 'FITC undefined'
}
var bar = '2015';
console.log(foo + ' ' + bar);
// Prints 'FITC 2015'
}
function scope4() {
var foo, bar;
foo = 'FITC';
if(!bar) {
console.log(foo + ' ' + bar);
// Prints 'FITC undefined'
}
bar = '2015';
console.log(foo + ' ' + bar);
// Prints 'FITC 2015'
}
// Function Scoping Sample 5
function scope5() {
var foo;
foo = 'FITC';
console.log(foo); // Prints 'FITC'
function foobar() {
var foo = 'BAR';
console.log(foo); // Prints 'BAR'
}
foobar();
console.log(foo); // Prints 'FITC'
}
// Function Scoping Sample 6 with let
function scope6() {
let foo = 'FITC';
console.log(foo); // Prints 'FITC'
if (true) {
let foo = 'BAR';
console.log(foo); // Prints 'BAR'
}
console.log(foo); // Prints 'FITC'
}
// Function Scoping Sample 7 with const
function scope7() {
const foo = 'FITC';
console.log(foo); // Prints 'FITC'
if (true) {
let foo = 'BAR';
console.log(foo); // Prints 'BAR'
}
// foo = 'BAR';
// Above causes SyntaxError: Assignment to constant variable.
console.log(foo); // Prints 'FITC'
}
// Destructuring Examples
function scope8(){
var [foo, bar, ABC] = ['bar', 'foo', 3];
console.log(foo + ' ' + bar + ' ' + ABC);
// Prints 'bar foo 3'
var foo = 'bar', bar = 'foo', ABC = 3;
console.log(foo + ' ' + bar + ' ' + ABC);
// Prints 'bar foo 3'
var [foo, bar] = ['bar', 'foo'];
[foo, bar] = [bar, foo];
console.log(foo + ' ' + bar);
// Prints 'foo bar'
// Object matching
// Simple example without assigning new names
var {x, y} = {x: "X", y: "Y"};
console.log(x); // X
console.log(y); // Y
// getTalk() returns -> { speaker: { name: "Rami" }, title: "Future of JS"}
var { title: talk_title, speaker: { name: speaker_name }} = getTalk(); 
console.log(talk_title); // "Future of JS"
console.log(speaker_name); // "Rami"
// Can be used in parameter position
function g({name: x}) {
console.log(x);
}
g({name: 5})
// Fail-soft destructuring
var [a] = [];
a === undefined;
// Fail-soft destructuring with defaults
var [a = 1] = [];
a === 1;
}
function scope9(){
class SkinnedMesh extends THREE.Mesh {
constructor(geometry, materials) {
super(geometry, materials);
this.idMatrix = SkinnedMesh.defaultMatrix();
this.bones = [];
this.boneMatrices = [];
//...
}
update(camera) {
//...
super.update();
}
get boneCount() {
return this.bones.length;
}
set matrixType(matrixType) {
this.idMatrix = SkinnedMesh[matrixType]();
}
static defaultMatrix() {
return new THREE.Matrix4();
}
}
}
function scope10() {
var obj, iterator, pair;
obj = { foo: 'bar', conference: 'FITC' };
iterator = Iterator(obj);
pair = it.next(); // ["foo", "bar"]
pair = it.next(); // ["conference", "FITC"]
pair = it.next(); // StopIteration exception thrown
var evangelists = ['@ramisayar', '@tommylee',
'@scruffyfurn'];
var iterator = Iterator(evangelists);
for (let [i, e] in iterator) {
console.log(i + ': ' + e);
// prints "0: @ramisayar" etc.
}
function *foo() {
var x = 2;
while(true){
x = x * x;
yield x;
}
}
var answer = foo();
answer.next(); // 4
answer.next(); // 16
function *foo() {
var x = 1, next = 1;
while(true) {
x = x * next;
next = yield x;
}
}
var answer = foo();
answer.next(); // 1
answer.send(2); // 2
answer.send(2); // 4
}
scope1();
scope2();
scope3();
scope4();
scope5();
scope6();
scope8();
scope7();
scope8();
scope9();
scope10();
var koa = require('koa');
var app = koa();
app.use(function *(){
this.body = 'Hello World';
});
app.listen(3000);
'use strict';
// math.js
export var pi = 3.141593;
export function add(num1, num2) {
return num1 + num2;
}
export function circle_area(r) {
return pi * r * r;
}
'use strict';
// otherApp.js
import {circle_area, pi} from "math";
alert("Area of Circle with Radius of 5 = " + circle_area(5));
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