[javascript] react 들어가기 전! javascript 복습 (실전2)

4. 조건문 업그레이드

 function isKoreanFood(food){
   //if(food === '불고기' || food === '비빔밥' || food === '떡볶이') {
   if(['불고기','떡볶이','비빔밥'].includes(food)) {

     return true;
   }
   return false;
 }

 const food1 = isKoreanFood("불고기");
 const food2 = isKoreanFood("파스타");

 console.log(food1);
 console.log(food2);

// const getMeal = (mealType) => {
//   if(mealType === '한식')return "불고기";
//   if(mealType === '양식')return "파스타";
//   if(mealType === '중식')return "자장면";
//   if(mealType === '일식')return "초밥";
//   return "굶기";
// };

// console.log(getMeal("한식"));
// console.log(getMeal("양식"));
// console.log(getMeal("중식"));
// console.log(getMeal("일식"));
// console.log(getMeal(""));

///////////////////////////////////////////->

const meal = {
  한식: "불고기",
  중식: "자장면",
  일식: "초밥",
  양식: "스테이크",
  인도식: "카레"
}

const getMeal = (mealType) => {
  return meal[mealType] || "굶기";
};

console.log(getMeal("한식"));
console.log(getMeal("중식"));
console.log(getMeal(""));

 

긴 조건문을 위와같은 방식으로 간단하게 줄여 쓸 수 있다.

---

5. 비 구조화 할당 (구조분해 할당)

let arr = ["one", "two", "three"];

// let one = arr[0];
// let two = arr[1];
// let three = arr[2];

//let [one, two, three] = arr;

//let [one, two, three] = ["one", "two", "three"];

let [one, two, three, four = "four"] = ["one", "two", "three"];

console.log(one, two, three, four);

let a = 10;
let b = 20;
let tmp = 0;

// tmp = a;
// a = b;
// b = tmp;

//위의 방법을 아래의 방법처럼 스왑하여 사용 가능
[a, b] = [b, a];
console.log(a, b);

let object = {one:"one", two:"two", three:"three", name: "이름"};

// let one = object.one;
// let two = object.two;
// let three = object.three;

let {one, two, three, name} = object;

console.log(one, two, three, name);

---

6. Spread 연산자

const cookie = {
  base: "cookie",
  madeIn: "korea"
};

const chocochipCookie = {
  ...cookie,
  toping: "chocochip"
};

const blueberryCookie = {
  ...cookie,
  toping: "blueberry"
};

const strawberryCookie = {
  ...cookie,
  toping: "strawberry"
};

console.log(chocochipCookie);
console.log(blueberryCookie);
console.log(strawberryCookie);

const noTopingCookies = ["촉촉한쿠키", "안촉촉한쿠키"];
const TopingCookies = ["바나나쿠키", "블루베리쿠키", "딸기쿠키", "초코칩쿠키"];

const allCookies = [...noTopingCookies, "함정쿠키", ...TopingCookies];
console.log(allCookies);