ES6 이후 추가된 문법

nullish coalescing

function printMessage(text){
    const message = text ?? 'Nothing to display' 
    console.log(message) // leftExpr ?? rightExpr 
                     //null,undefined
}
function printMessage(text = 'Nothing to display'){
    console.log(text) // text인자가 undefined일때만, 'Nothing to display'출력 -> default parameter, 
}
printMessage('Hello')
printMessage(undefined)
printMessage(null)

leftExpr || rightExpr === logical operator

destructuring 구조분해

{name, age} = person

spread syntax - object

const shirt0 = Object.assign(item, detail)
const shirt = {...item, ...detail, price:40} // update도 가능

spread syntax - array

let fruits = ['apple','banana','peach']
fruits = [...fruits, 'pineapple'] // push와 같은기능

optional chaining

배열 중복제거

let fruits = ['apple','banana','peach','peach','banana','apple']

console.log([...new Set(fruits)])