문자열, 배열, 함수, 객체

문자열

let str =`
Hi,
This is jirengu.com.
You can study frontend here.
`

let website = 'jirengucom'
let who = 'You'
let str = `Hi
This is ${website}.
${who} can study frontend here
`

배열

var a = [1, 2]
console.log(...a)  // 1, 2
var b = [...a, 3]
b // [1, 2, 3]

var c = b.concat([4, 5])
var d = [...b, 4, 5]

function sort(...arr){
  console.log(arr.sort())
}
sort(3, 1, 5)  //[1, 3, 5]

function max(arr){
  return Math.max(...arr)
}
max([3, 4, 1])  // 4

let ps = document.querySelectorAll('p');
Array.from(ps).forEach(p=> {
  console.log(p.innerText);
});
[...ps].forEach(p=>{console.log(p.innerText)});

함수.

function sayHi(name='jirengu') {
  console.log(`hi, ${name}`)
}
sayHi()
sayHi('ruoyu')

function fetch(url, { body='', method = 'GET', headers = {} } = {}) {
  console.log(method);
}

fetch('http://example.com')

//ex1
function m1({x = 0, y = 0} = {}) {
  return [x, y];
}

//ex2 
function m2({x, y} = { x: 0, y: 0 }) {
  return [x, y];
}

//  
m1() // [0, 0]
m2() // [0, 0]

// x   y  
m1({x: 3, y: 8}) // [3, 8]
m2({x: 3, y: 8}) // [3, 8]

// x  ，y  
m1({x: 3}) // [3, 0]
m2({x: 3}) // [3, undefined]

// x   y  
m1({}) // [0, 0];
m2({}) // [undefined, undefined]

m1({z: 3}) // [0, 0]
m2({z: 3}) // [undefined, undefined]

var f = v => v+1
// 
var f = function(v){return v+1}

var f = () => 5;
//  
var f = function () { return 5 };

var sum = (num1, num2) => num1 + num2;
//  
var sum = function(num1, num2) {
  return num1 + num2;
};

var arr = [1, 2, 3]
var arr2 = arr.map(v=>v*v)
arr2 //[1, 4, 9]

// ES6
function foo() {
  setTimeout(() => {
    console.log('id:', this.id);
  }, 100);
}

//   ES5
function foo() {
  var _this = this;
  setTimeout(function () {
    console.log('id:', _this.id);
  }, 100);
}

대상

var name = 'jirengu'
var age = 3
var people = {name, age} //{name:'jirengu', age:3}

let app = {
   selector: '#app',
   init() {
   },
   bind() {
   } 
}
app.init()

``