chaerynny

Object.prototype.obj = function () {};
Array.prototype.arr = function () {};

var iterable = [3, 5, 7];
iterable.f = "hello";

for (var key in iterable) {
  console.log(key); // 0, 1, 2, "f", "arr", "obj"
}

chaerynny

const obj = { a: 1, b: 2, c: 3 };

Object.prototype.obj2 = function() { 
  return 0;
}

for (const key in obj) {
  console.log(key, obj[key]);
} // a 1 b 2 c 3 obj function()...

chaerynny

const arr = [1, 2, 3, 4, 5];
arr.forEach(item => console.log(item); ); // 1, 2, 3, 4, 5

chaerynny

// ES5
var array = ["apple", "banana", "pineapple"];
for (var i = 0; i < array.length; i++) {
  console.log(array[i]);
}

var string = 'hello world';
for (var i = 0; i < string.length; i++) {
  console.log(string[i]);
}

chaerynny

// ES5
var double = function(num) {
  return num * 2;
}

// ES6
let double = num => num * 2;

// 화살표 함수에서의 this
console.log(this === window); // true

chaerynny

// ES5
let iAm = function(name, age, country) {
  return name + ',' + age + ',' + country;
}

// ES6
let iAm = function(name, age, country = 'South Korea') {
  return `${name}, ${age}, ${country}`;
}

chaerynny

// ES5
let iAm = function(name, age, country) {
  country = country === undefined? 'South Korea' : country;
}
console.log(iAm('ryn', 20)); // 'ryn', 20, 'South Korea'
console.log(iAm('ryn', 20, 'Canada')); // 'ryn', 20, 'Canada'

// ES6
let iAm = function(name, age, country = 'South Korea') {
  country = country === undefined? 'South Korea' : country;

chaerynny

let array = ["apple", "banana", "pineapple"];
let newArr = [...array];
console.log( newaArr === array );  // false, 원본 배열을 바꾸지 않음

// Spread Operator 활용
function sum(a, b, c){
  return a + b + c;
}
let array = [100, 200, 300];

chaerynny

// Array
// ES5
var array = [1, 2, 3];

var apple = array[0]; // 1
var banana = array[1]; // 2

// ES6
var array = [1, 2, 3];
var [apple, banana] = array; 

chaerynny

class Node {
  constructor(value) {
    this.value = value; // 데이터 값
    this.next = null; // 다음 노드
  }
}

class LinkedList {
  constructor() {
    this.head = null; // 시작노드