2nd/10_Wiki/Topic_JavaScript/JavaScript_Class_Static.md

---
id: javascript-class-static
title: "JavaScript Class Static"
category: "Frontend"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["static methods", "static keyword", "class-level method", "Car.hello", "static members"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.88
created_at: 2026-06-23
updated_at: 2026-06-23
review_reason: ""
merge_history: []
tags: ["javascript", "js", "web", "frontend", "w3schools", "classes", "static", "oop"]
raw_sources: ["https://www.w3schools.com/js/js_class_static.asp"]
applied_in: []
github_commit: ""
---

# [[JavaScript Class Static]]

## 🎯 한 줄 통찰 (One-line insight)
Static methods are defined with the `static` keyword on the class itself and can only be called on the class, not on its objects — pass an object in as a parameter if a static method needs instance data. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Static methods live on the class** — static class methods are defined on the class itself. [S1]
- **Call on the class, not the object** — you cannot call a `static` method on an object, only on an object class. [S1]
- **Use a parameter for instance data** — to use an object within a static method, send it as a parameter. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **`static` for class-level utilities** — declare methods with `static` when they belong to the class rather than to any single instance. [S1]
- **Inject the instance** — when a static method needs object state, pass the object in (e.g. `Car.hello(myCar)`) since `this` will not be an instance. [S1]

## 📖 세부 내용 (Details)
**Static Methods**
Static class methods are defined on the class itself. You cannot call a `static` method on an object, only on an object class: [S1]
```javascript
class Car {
  constructor(name) {
    this.name = name;
  }
  static hello() {
    return "Hello!!";
  }
}

const myCar = new Car("Ford");

// You can call 'hello()' on the Car Class:
document.getElementById("demo").innerHTML = Car.hello();

// But NOT on a Car Object:
// document.getElementById("demo").innerHTML = myCar.hello();
// this will raise an error.
```

**Passing an Object to a Static Method**
If you want to use an object inside a static method, you can send it as a parameter: [S1]
```javascript
class Car {
  constructor(name) {
    this.name = name;
  }
  static hello(x) {
    return "Hello " + x.name;
  }
}
const myCar = new Car("Ford");
document.getElementById("demo").innerHTML = Car.hello(myCar);
```

## 🛠️ 적용 사례 (Applied in summary)
The `Car.hello()` examples are the canonical applied cases — one showing that the static method is callable only on the class, the other showing the object passed in as a parameter to access `x.name`. No external project/commit applications found in the source.

## 💻 코드 패턴 (Code patterns)
Declare and call a static method on the class (language: JavaScript):
```javascript
class Car {
  constructor(name) { this.name = name; }
  static hello() { return "Hello!!"; }
}
Car.hello();        // ✅ on the class
// myCar.hello();   // ❌ on an object → error
```
Pass an instance into a static method:
```javascript
static hello(x) { return "Hello " + x.name; }
Car.hello(myCar);
```

## ⚖️ 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:** 0.88
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[JavaScript Tutorial]]
- **관련 개념:** [[JavaScript Classes]], [[JavaScript Class Inheritance]], [[JavaScript Objects]], [[JavaScript Object Methods]]
- **참조 맥락:** Extends JavaScript Classes with class-level (static) methods and their call-site restriction.

## 📚 출처 (Sources)
- [S1] W3Schools — JavaScript Class Static — https://www.w3schools.com/js/js_class_static.asp

## 📝 변경 이력 (Change history)
- 2026-06-23: Initial draft synthesized from the W3Schools "JavaScript Class Static" page (Astra wiki-curation, P-Reinforce v3.1 format).