docs(10_Wiki): W3Schools 위키화 — HTML/CSS/JavaScript(core)

W3Schools 튜토리얼을 P-Reinforce v3.1 포맷으로 위키화(영어 본문, 한/영 섹션 헤더).
- Topic_HTML: 59문서 (튜토리얼+예제, 레퍼런스/메타 제외)
- Topic_CSS: 190문서 (메인 + Advanced/Flexbox/Grid/RWD 전체)
- Topic_JavaScript: 120문서 (코어 언어; Temporal/DOM상세/BOM/WebAPI/AJAX/jQuery/Graphics 등은 후속)
각 폴더 00_INDEX.md(MOC) 포함. 코드 verbatim, 미확인분은 "Not found in source" 표기.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

10_Wiki/Topic_JavaScript/JavaScript_Classes.md

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+---
+id: javascript-classes
+title: "JavaScript Classes"
+category: "Frontend"
+status: "draft"
+verification_status: "conceptual"
+canonical_id: ""
+aliases: ["ES6 classes", "class syntax", "constructor method", "class methods", "use strict"]
+duplicate_of: ""
+source_trust_level: "B"
+confidence_score: 0.89
+created_at: 2026-06-23
+updated_at: 2026-06-23
+review_reason: ""
+merge_history: []
+tags: ["javascript", "js", "web", "frontend", "w3schools", "classes", "oop", "es6"]
+raw_sources: ["https://www.w3schools.com/js/js_classes.asp"]
+applied_in: []
+github_commit: ""
+---
+
+# [[JavaScript Classes]]
+
+## 🎯 한 줄 통찰 (One-line insight)
+A JavaScript class, introduced in ES6, is a template for objects (not an object itself), defined with the `class` keyword and a `constructor()` method that runs automatically on `new`. [S1]
+
+## 🧠 핵심 개념 (Core concepts)
+- **Classes are ES6 templates** — a class is a template for JavaScript objects, defined with the `class` keyword and a `constructor()` method. [S1]
+- **A class is not an object** — it is a template from which objects are created. [S1]
+- **The constructor runs automatically** — the `constructor` method is called automatically when a new object is created with `new`. [S1]
+- **Constructor rules** — it must use the exact name `constructor`, executes automatically, and initializes properties. [S1]
+- **Class methods** are defined inside the class body and can take parameters. [S1]
+- **Strict mode** — classes require "strict mode" compliance (e.g. variables must be declared with `const`/`let`). [S1]
+
+## 🧩 추출된 패턴 (Extracted patterns)
+- **constructor + `this` initialization** — assign incoming arguments to `this.*` in the constructor to set up object state. [S1]
+- **Method computes from state** — methods like `age()` derive values from the instance's own properties (e.g. `this.year`). [S1]
+- **Pass external data as a parameter** — when a method needs outside data (like the current year), pass it in as an argument rather than recomputing. [S1]
+
+## 📖 세부 내용 (Details)
+**JavaScript Class Syntax**
+ES6 introduced JavaScript Classes as templates for objects. The basic syntax uses the `class` keyword with a `constructor()` method: [S1]
+```javascript
+class ClassName {
+  constructor() { ... }
+}
+```
+A concrete example: [S1]
+```javascript
+class Car {
+  constructor(name, year) {
+    this.name = name;
+    this.year = year;
+  }
+}
+```
+A JavaScript class is **not** an object. It is a **template** for JavaScript objects. [S1]
+
+**Using a Class**
+Instantiate with `new`: [S1]
+```javascript
+const myCar1 = new Car("Ford", 2014);
+const myCar2 = new Car("Audi", 2019);
+```
+The constructor method is called automatically when a new object is created. [S1]
+
+**The Constructor Method**
+The constructor must use the exact name `constructor`, executes automatically when objects are created, and initializes properties. [S1]
+
+**Class Methods**
+A method computing the car's age from `this.year`: [S1]
+```javascript
+class Car {
+  constructor(name, year) {
+    this.name = name;
+    this.year = year;
+  }
+  age() {
+    const date = new Date();
+    return date.getFullYear() - this.year;
+  }
+}
+
+const myCar = new Car("Ford", 2014);
+document.getElementById("demo").innerHTML =
+"My car is " + myCar.age() + " years old.";
+```
+A method that accepts a parameter: [S1]
+```javascript
+class Car {
+  constructor(name, year) {
+    this.name = name;
+    this.year = year;
+  }
+  age(x) {
+    return x - this.year;
+  }
+}
+
+const date = new Date();
+let year = date.getFullYear();
+
+const myCar = new Car("Ford", 2014);
+document.getElementById("demo").innerHTML=
+"My car is " + myCar.age(year) + " years old.";
+```
+
+**"use strict"**
+Classes require "strict mode" compliance — variables must be properly declared: [S1]
+```javascript
+class Car {
+  constructor(name, year) {
+    this.name = name;
+    this.year = year;
+  }
+  age() {
+    // date = new Date();  // This will not work
+    const date = new Date(); // This will work
+    return date.getFullYear() - this.year;
+  }
+}
+```
+
+## 🛠️ 적용 사례 (Applied in summary)
+The `Car` class is the running applied example — defining name/year in the constructor, deriving age in a method (with and without a parameter), and demonstrating strict-mode variable declaration. No external project/commit applications found in the source.
+
+## 💻 코드 패턴 (Code patterns)
+Define a class and instantiate it (language: JavaScript):
+```javascript
+class Car {
+  constructor(name, year) {
+    this.name = name;
+    this.year = year;
+  }
+}
+const myCar1 = new Car("Ford", 2014);
+```
+Add a method that uses instance state:
+```javascript
+age() {
+  const date = new Date();
+  return date.getFullYear() - this.year;
+}
+```
+
+## ⚖️ 모순 및 업데이트 (Contradictions & updates)
+No contradictions found in the source.
+
+## ✅ 검증 상태 및 신뢰도
+- **상태:** draft
+- **검증 단계:** conceptual (실제 적용 사례 발견 시 applied/validated로 승격 가능)
+- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
+- **신뢰 점수:** 0.89
+- **중복 검사 결과:** 신규 생성 (New discovery)
+
+## 🔗 지식 그래프 (Knowledge Graph)
+- **상위/루트:** [[JavaScript Tutorial]]
+- **관련 개념:** [[JavaScript Class Inheritance]], [[JavaScript Class Static]], [[JavaScript Objects]], [[JavaScript Object Constructors]]
+- **참조 맥락:** The foundation for object-oriented JavaScript; extended by class inheritance and static-method pages.
+
+## 📚 출처 (Sources)
+- [S1] W3Schools — JavaScript Classes — https://www.w3schools.com/js/js_classes.asp
+
+## 📝 변경 이력 (Change history)
+- 2026-06-23: Initial draft synthesized from the W3Schools "JavaScript Classes" page (Astra wiki-curation, P-Reinforce v3.1 format).