`Fifteen is ${a + b} and not ${2 * a + b}.`

function Person() {
    this.age = 0;
    // var self = this;

    // 定義該 Arrow Functions 時的環境，是在 Person 物件中
    setInterval(() => {
        // 所以 this 會正確指向 Person 物件
        this.age++;
        //self.age++
    }, 1000);
}

var p = new Person();

class Animal { 
    constructor(name) {
        this.name = name;
    }
  
    speak() {
        console.log(this.name + ' makes a noise.');
    }
    static triple(n) {
        if (n === undefined) {
            n = 1;
        }
        return n * 3;
  }
}

class Dog extends Animal {
    constructor(name) {
        super(name)
        this.name = name;
    }
    speak() {
        super.speak() // this會用到子類別的obj
        console.log(this.name + ' barks.');
    }
    static triple(n) {
        return super.triple(n) * super.triple(n);
    }
}

var d = new Dog('Mitzie');

// 顯示 Mitzie barks.
d.speak();

// export [default] <exp with var>
// var ..., function, class 

export { encrypt };
export { decrypt as dec };

import {aString, aObject, aFunction, aClass} from './lib.js'
import  * as myModule from './lib.js'

var prefix = 'es6';

var obj = {
    // 計算屬性
    [prefix + ' is']: 'cool',
    
    // 計算方法
    [prefix + ' score']() {
        console.log(100);
    }
};
 
// 顯示 cool
console.log(obj['es6 is']);

// 顯示 100
obj['es6 score']();