# 10.3 셋 (Set)

### 셋의 특징

* 중복을 허용하지 않는 데이터 집합 => 추가하려는 것이 이미 있는지 확인할 필요 없음
* 만약 추가하려는 것이 이미 있다면?
  * 아무 일도 일어나지 않음

#### add() 메서드

* 데이터를 추가할 때

#### delete() 메서드

* 데이터를 삭제할 때
* 제거에 성공 => true, 실패 => false 반환

```javascript
  const roles = new Set();

  // 사용자 역할 추가
  roles.add("User");

  // 사용자에게 관리자 역할 추가
  roles.add("Admin");

  roles.size;

  console.log(roles); // Set(2) {"User", "Admin"}
  console.log(roles.size); // 3

  roles.delete("Admin");
  console.log(roles); // Set(1) {"User"}
```


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