2nd/10_Wiki/Topic_JavaScript/JavaScript_If_Else.md

id, title, category, status, verification_status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, created_at, updated_at, review_reason, merge_history, tags, raw_sources, applied_in, github_commit

id	title	category	status	verification_status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	created_at	updated_at	review_reason	merge_history	tags	raw_sources	applied_in	github_commit
javascript-if-else	JavaScript If Else	Frontend	draft	conceptual		JS if else else statement else if statement if else if chain if else syntax branching		B	0.89	2026-06-23	2026-06-23			javascript js web frontend w3schools if-else control-flow	https://www.w3schools.com/js/js_if_else.asp

JavaScript If Else

🎯 한 줄 통찰 (One-line insight)

Use else to run a block when the condition is false, and else if to test a new condition when the first is false, forming a multi-branch decision chain. [S1]

🧠 핵심 개념 (Core concepts)

• else handles the false case — use the else statement to specify a block of code to be executed if a condition is false. [S1]
• else if chains a new test — use the else if statement to specify a new condition if the first is false. [S1]
• First-true-wins — in an if / else if / else chain, the first branch whose condition is true runs, and the trailing else is the fallback when all conditions are false. [S1]
• Builds on if — else and else if extend the basic if statement rather than replacing it. [S1]

🧩 추출된 패턴 (Extracted patterns)

• Two-way branch — if (...) { ... } else { ... } to pick exactly one of two blocks. [S1]
• Multi-way ladder — chain else if for graduated thresholds (e.g. time-of-day greeting). [S1]
• Branch then render — compute a value in branches, then write it to the DOM (innerHTML). [S1]

📖 세부 내용 (Details)

The else Statement [S1] Use the else statement to specify a block of code to be executed if a condition is false.

Syntax: [S1]

if (condition) {
  // block of code to be executed if the condition is true
} else {
  // block of code to be executed if the condition is false
}

Example — time-of-day greeting: [S1]

if (hour < 18) {
  greeting = "Good day";
} else {
  greeting = "Good evening";
}

The else if Statement [S1] Use the else if statement to specify a new condition if the first is false.

Syntax: [S1]

if (condition1) {
  // block of code to be executed if condition1 is true
} else if (condition2) {
  // block of code to be executed if the condition1 is false and condition2 is true
} else {
  // block of code to be executed if the condition1 is false and condition2 is false
}

Example — three-way greeting: [S1]

if (time < 10) {
  greeting = "Good morning";
} else if (time < 20) {
  greeting = "Good day";
} else {
  greeting = "Good evening";
}

Example — branch then render to the page: [S1]

let text;
if (Math.random() < 0.5) {
  text = "<a href='https://w3schools.com'>Visit W3Schools</a>";
} else {
  text = "<a href='https://wwf.org'>Visit WWF</a>";
}
document.getElementById("demo").innerHTML = text;

🛠️ 적용 사례 (Applied in summary)

The page's own snippets are the canonical applied examples — a two-way greeting, a three-way else if greeting ladder, and a random-link example that branches then writes the result into #demo via innerHTML. No external project/commit applications found in the source.

💻 코드 패턴 (Code patterns)

Two-way branch:

if (hour < 18) {
  greeting = "Good day";
} else {
  greeting = "Good evening";
}

Multi-way ladder with else if:

if (time < 10) {
  greeting = "Good morning";
} else if (time < 20) {
  greeting = "Good day";
} else {
  greeting = "Good evening";
}

⚖️ 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 If, JavaScript Conditional Operators, JavaScript Comparisons, JavaScript Introduction
• 참조 맥락: Referenced whenever a decision needs more than a single true-only branch.

📚 출처 (Sources)

• [S1] W3Schools — JavaScript If Else — https://www.w3schools.com/js/js_if_else.asp

📝 변경 이력 (Change history)

• 2026-06-23: Initial draft synthesized from the W3Schools "JavaScript If Else" page (Astra wiki-curation, P-Reinforce v3.1 format).