---
id: javascript-comments
title: "JavaScript Comments"
category: "Frontend"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["JS comments", "single line comment", "multi-line comment", "block comment", "prevent execution"]
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", "comments"]
raw_sources: ["https://www.w3schools.com/js/js_comments.asp"]
applied_in: []
github_commit: ""
---

# [[JavaScript Comments]]

## 🎯 한 줄 통찰 (One-line insight)
JavaScript comments explain code and improve readability — single-line comments start with `//`, multi-line comments are wrapped in `/* */`, and either form can also be used to prevent code from executing. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Purpose of comments** — comments can be used to explain JavaScript code and to make it more readable; they can also be used to prevent execution when testing alternative code. [S1]
- **Single line comments** — start with `//`; any text between `//` and the end of the line is ignored (not executed). [S1]
- **Multi-line comments** — start with `/*` and end with `*/`; any text between is ignored. [S1]
- **Comments to prevent execution** — placing `//` or `/* */` around code lines is a convenient way to prevent execution, e.g. while debugging. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **End-of-line annotation** — append `// ...` after a statement to document what that line does. [S1]
- **Block intro comment** — use a `/* ... */` block before a group of statements to describe what the following code does. [S1]
- **Comment-out for debugging** — prefix a single line with `//`, or wrap several lines in `/* */`, to temporarily disable them. [S1]

## 📖 세부 내용 (Details)
**Single Line Comments** — Single line comments start with `//`. Any text between `//` and the end of the line will be ignored by JavaScript (will not be executed). This example uses a single line comment before each line of code: [S1]
```javascript
// Change heading:
document.getElementById("myH").innerHTML = "My First Page";

// Change paragraph:
document.getElementById("myP").innerHTML = "My first paragraph.";
```
This example uses a single line comment at the end of each line to explain the code: [S1]
```javascript
let x = 5;      // Declare x, give it the value of 5
let y = x + 2;  // Declare y, give it the value of x + 2
```

**Multi-line Comments** — Multi-line comments start with `/*` and end with `*/`. Any text between `/*` and `*/` will be ignored by JavaScript. This example uses a multi-line comment (a comment block) to explain the code: [S1]
```javascript
/*
The code below will change
the heading with id = "myH"
and the paragraph with id = "myP"
in my web page:
*/
document.getElementById("myH").innerHTML = "My First Page";
document.getElementById("myP").innerHTML = "My first paragraph.";
```

**Using Comments to Prevent Execution** — Using comments to prevent execution of code is suitable for testing. Adding `//` in front of a code line changes the lines from an executable line to a comment: [S1]
```javascript
//document.getElementById("myH").innerHTML = "My First Page";
document.getElementById("myP").innerHTML = "My first paragraph.";
```
This example uses a comment block to prevent execution of multiple lines: [S1]
```javascript
/*
document.getElementById("myH").innerHTML = "My First Page";
document.getElementById("myP").innerHTML = "My first paragraph.";
*/
```

## 🛠️ 적용 사례 (Applied in summary)
The page's own snippets are the canonical applied examples — single-line intro/end-of-line comments, a multi-line explanatory block, and commenting out one line vs a multi-line block to prevent execution. No external project/commit applications found in the source.

## 💻 코드 패턴 (Code patterns)
Single line, end-of-line:
```javascript
let x = 5;      // Declare x, give it the value of 5
```
Multi-line block:
```javascript
/*
This block describes the code below.
*/
```
Comment out to disable:
```javascript
//document.getElementById("myH").innerHTML = "My First Page";
```

## ⚖️ 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 Syntax]], [[JavaScript Statements]], [[JavaScript Variables]]
- **참조 맥락:** Documentation practice referenced across every code example in the tutorial.

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

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