FITC - What's New in ES6 for Web Devs - Sample code from my presentation

app.js

'use strict';

// app.js
import * as math from "math";
alert("2π = " + math.add(math.pi, math.pi));

es6_samples.js

'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();

koa_app.js

var koa = require('koa');
var app = koa();

app.use(function *(){
  this.body = 'Hello World';
});

app.listen(3000);

math.js

'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;
}

otherApp.js

'use strict';

// otherApp.js
import {circle_area, pi} from "math";
alert("Area of Circle with Radius of 5 = " + circle_area(5));