July 2017
Beginner to intermediate
464 pages
10h 38m
Korean
Content preview from 러닝 자바스크립트: ES6로 제대로 입문하는 모던 자바스크립트 웹 개발
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237
9
장
객체와 객체지향 프로그래밍
자바스크립트의 모든 객체는 루트 클래스인
Object
의 인스턴스입니다. 즉, 객체
o
에서
o
instanceof
Object
는 항상
true
입니다(__
proto
__ 프로퍼티를 수정한다면 다른 결과가 나올 수
있지만, 그렇게 해서는 안 됩니다). 모든 객체가
Object
의 인스턴스인 것은
toString
같은 중요한 메서드
를 상속하기 위해서이며, 염두에 둘 만큼 중요한 영향은 없습니다.
9.2.7
객체 프로퍼티 나열 다시 보기
for
...
in
문으로 객체의 프로퍼티를 나열하는 방법은 이미 봤습니다. 이제 프로토타입 상속에
대해 알게 됐으니 객체의 프로퍼티를 나열할 때
hasOwnProperty
가 어떤 의미가 있는지 완전히
이해할 수 있습니다. 객체
obj
와 프로퍼티
x
에서,
obj
.
hasOwnProperty
(
x
)
는
obj
에 프로퍼티
x
가 있다면
true
를 반환하며, 프로퍼티
x
가
obj
에 정의되지 않았거나 프로토타입 체인에만 정
의되었다면
false
를 반환합니다.
ES6
클래스를 설계 의도대로 사용한다면 데이터 프로퍼티는 항상 프로토타입 체인이 아니라
인스턴스에 정의해야 합니다. 하지만 프로퍼티를 프로토타입에 정의하지 못하도록 강제하는
장치는 없으므로 확실히 확인하려면 항상
hasOwnProperty
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.