[20220602 T]

🎈ARRAY

const arr = [1,2,3]

console.log(Array.isArray(arr))

🎈구조분해 할당

function formatDate(targetDate){
	const [date] = targetDate.toISOString().split("T");
    
    const [year, momth, day] = date.split("-");
    
    return `${year}년 ${month}월 ${day}일`
}

🎈Lodash처럼 유틸함수 만들기

funtion head(arr){
	return arr[0] ??  ""
}

🎈유사 배열 객체

자바스크립의 배열은 객체 like 노드리스트, arguments

const arrayLikeObject = {

0: "Hello",
1: "World".
length: 2

}

Array.isArray
Array.from

const sufficWon = price => price + "원";
const isOverOneThousand = price => Number(price) > 1000
const ansendingList = (a,b) => a-b;

//function getWonPrice(priceList){
	const isOverList = priceList.filter(isOverOneThousand);
   	const sortList = isOverList.sort(ascendingList);
    
    return sortList.map(suffixWon);
}//

function getWonPrice(priceList){

    return priceList
    .filter(isOverOneThousand)
    .sort(ascendingList)
    .map(suffixWon);
}

🎈 배열 매서드 체이닝

🎈 map vs forEach

Array.prototype.every() AND
Array.prototype.some() OR
Array.prototype.find()
Array.prototype.findIndex()

🎈 LOOKUP TABLE

function getUserType(type){
	const USER_TYPE={
    	ADMIN:"관리자",
        INSTRUCTOR:"강사",
        STUDENT:"학생"
    }
    
    return USER_TYPE[type]|| "해당없음"
}

function getUserType(type){
	return(
    	{
        	ADMIN: "관리자",
            INSTRUCTOR :"강사",
            STUDENT:"수강생",
        }[type] ?? "해당없음"
    )
}

🎈 객체 구조분해할당

function Person(name, {age, location}){
	this.name = name;
    this.age = age;
    this.location = location;

}

const pocoOptions = {
	age: 30,
    location: "Korea"
}

const poco = new Person("poco", pocoOptions)

const orders = ["first", "second", "third"];

const {0: st2, 2: rd2} = orders;

console.log(st2);
console.log(rd2);

or

const [st2, ,rd3] = orders;

🎈 Object.freeze

Object.isFrozen(STATUS)

🎈 shallow copy vs deep copy

Object.keys
Object.values
Object.entries