Tag: ES6

var camper = 'James';
var camper = 'David'; //no error

let camper = 'James';
let camper = 'David'; // throws an error

"use strict";
x = 3.14; // throws an error because x is not declared

const FAV_PET = "Cats";
FAV_PET = "Dogs"; // returns error

const s = [10, 11, 12];
s = [1, 2, 3]; // throws error, trying to assign a const
s[2] = 45; // works just as it would with an array declared with var or let
s.pop(45); //also works fine

var magic = function() {
  return new Date();
};

/* arrow function syntax */
const magic = () => {
  return new Date();
};

/* If there is no function body and only a return, omit the keyword return as well as the backets */
const magic = () => new Date();

const doubler = (item) => item * 2;
doubler(6); // returns 12

/* If you have a single parameter, omit the parentheses */
const doubler = item => item * 2;

const multiplier = (item, multi) => item * multi;
multiplier(6, 2); // returns 12

const hello = (name = "World") => "Hello " + name;

console.log(hello("Mars")); // Hello Mars
console.log(hello()); // Hello World

function howMany(...arguments) {
  return "You passed " + arguments.length + " arguments.";
}
console.log(howMany(0, 1, 2)); // You passed 3 arguments.

const array = [2, 99, 7, 4];

/* workaround in ES5 */
var max = Math.max.apply(null, array); // returns 99

/* ES6 */
const max = Math.max(...array); // returns 99

const person = { name: 'Max', age: 30 };

/* ES5 */
const name = person.name; // name = 'Max'
const age = person.age; // age = 30

/* ES6 */
const { name, age } = person; // name = 'Max', age = 30
// It even allows you to assign a new variable name
const { name: personName, age: personAge } = user; // personName = 'Max', personAge = 30

const [a, b,,, c] = [1, 2, 3, 4, 5, 6, 7];
console.log(a, b, c); // 1, 2, 5

// or collect the rest of the elements into a separate array
const [a, b, ...array] = [1, 2, 3, 4, 5, 7];
console.log(a, b); // 1, 2
console.log(array); // [3, 4, 5, 7]

const stats = {
  max: 56.78,
  standard_deviation: 4.34,
  median: 34.54,
  mode: 23.87,
  min: -0.75,
  average: 35.85
};

const half = ({max, min}) => (max + min) / 2.0; 

const person = {
  name: "Zodiac Hasbro",
  age: 56
};

const greeting = `Hello, my name is ${person.name}!
I am ${person.age} years old.`;

console.log(greeting); // prints
// Hello, my name is Zodiac Hasbro!
// I am 56 years old.

const createPerson = (name, age, gender) => {
  return {
    name: name,
    age: age,
    gender: gender
  };
};

/* Eliminates the redundancy of having to write x: x */
const createPerson = (name, age, gender) => ({
    name,
    age,
    gender
  });

/* ES5 function declaration */
const person = {
  name: "Max",
  sayHello: function() {
    return `Hello! My name is ${this.name}.`;
  }
};

/* ES6 */
const person = {
  name: "Max",
  sayHello() {
    return `Hello! My name is ${this.name}.`;
  }
};
person.sayHello();

/* ES5 */
var SpaceShuttle = function(targetPlanet){
  this.targetPlanet = targetPlanet;
}
var zeus = new SpaceShuttle('Mars');


/* ES6 */
class SpaceShuttle {
  constructor(targetPlanet) {
    this.targetPlanet = targetPlanet;
  }
}
const zeus = new SpaceShuttle('Mars');

class Thermostat {
    constructor(temperatureFahrenheit) {
        this._temperatureCelsius = 5/9 * (temperatureFahrenheit - 32);
    }
    //getter
    get temperature() {
        return this._temperatureCelsius;
    }
    //setter
    set temperature(updateTemperatureCelsius) {
        this._temperatureCelsius = updateTemperatureCelsius;
    }
}

const thermos = new Thermostat(76); // Setting in Fahrenheit scale
let temp = thermos.temperature; // 24.44 in Celsius
thermos.temperature = 26; // use setter
temp = thermos.temperature; // 26 in Celsius

<script type="module" src="string_functions.js"></script>

const uppercaseString = (string) => string.toUpperCase();
const lowercaseString = (string) => string.toLowerCase();

export {uppercaseString, lowercaseString};

/* import specific functions */
import { uppercaseString, lowercaseString } from './string_functions.js';

uppercaseString("hello");
lowercaseString("WORLD!");

/* import all */
import * as stringFunctions from './string_functions.js';
stringFunctions.uppercaseString("hello");
stringFunctions.lowercaseString("WORLD!");

const makeServerRequest = new Promise((resolve, reject) => {
  // responseFromServer represents a response from a server
  let responseFromServer;
    
  if(responseFromServer) {
    resolve("We got the data");
  } else {  
    reject("Data not received");
  }
});

makeServerRequest.then(result => {
  console.log(result);
})

makeServerRequest.catch(error => {
  console.log(error);
});