2nd/10_Wiki/Topics/Domain_Programming/Topic_JavaScript/JavaScript_Break.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-break	JavaScript Break	Frontend	draft	conceptual		break statement JS break labeled break break continue break label		B	0.89	2026-06-23	2026-06-23			javascript js web frontend w3schools break loops labels control-flow	https://www.w3schools.com/js/js_break.asp

JavaScript Break

🎯 한 줄 통찰 (One-line insight)

The break statement jumps out of a loop or switch; with a label, it can jump out of any code block. [S1]

🧠 핵심 개념 (Core concepts)

• Jumps out — the break statement "jumps out" of loops and switches, terminating execution immediately. [S1]
• Break in loops — when break is reached in a loop, the loop terminates immediately and control transfers to the statements following the loop; no further iterations execute. [S1]
• Break in a switch — in a switch, break exits the block after a matching case executes; without it, execution falls through to subsequent cases. [S1]
• Labels — a label is an identifier followed by a colon (labelname: statement;), and break labelname; jumps out of the labeled block. [S1]
• Only break and continue jump out of a block — break and continue are the only JavaScript statements that can jump out of a code block; without a label, break only exits loops or switches. [S1]

🧩 추출된 패턴 (Extracted patterns)

• Early exit on a sentinel — test a condition inside the loop and break when it is met. [S1]
• Labeled break for nested loops — name outer/inner loops and break loop1; / break loop2; to control exactly which loop terminates. [S1]
• Break out of a plain code block — label a { ... } block and break label; to skip the remaining statements. [S1]

📖 세부 내용 (Details)

The break statement [S1] The break statement "jumps out" of loops and switches, terminating execution of a loop or switch statement immediately.

Break in loops [S1] When break is encountered in a loop, the loop terminates immediately and control transfers to the statements following the loop. No further iterations execute.

for (let i = 0; i < 10; i++) {
  if (i === 3) { break; }
  text += "The number is " + i + "<br>";
}

Break in a switch [S1] In a switch statement, break exits the block after a matching case executes. Without it, execution "falls through" to subsequent cases.

switch (new Date().getDay()) {
  case 0:
    day = "Sunday";
    break;
  case 1:
    day = "Monday";
    break;
  case 2:
     day = "Tuesday";
    break;
  case 3:
    day = "Wednesday";
    break;
  case 4:
    day = "Thursday";
    break;
  case 5:
    day = "Friday";
    break;
  case 6:
    day = "Saturday";
}

JavaScript labels [S1] A label is an identifier followed by a colon: labelname: statement;. A labeled break uses the syntax break labelname;.

Break to loop1 [S1]

let text = "";

loop1: for (let j = 1; j < 5; j++) {
  loop2: for (let i = 1; i < 5; i++) {
    if (i === 3) { break loop1; }
    text += i;
   }
}

Break to loop2 [S1]

let text = "";

loop1: for (let j = 1; j < 5; j++) {
  loop2: for (let i = 1; i < 5; i++) {
    if (i === 3) { break loop2; }
    text += i;
   }
}

Break out of a code block [S1]

const cars = ["BMW", "Volvo", "Saab", "Ford"];
list: {
  text += cars[0] + "<br>";
  text += cars[1] + "<br>";
  break list;
  text += cars[2] + "<br>";
  text += cars[3] + "<br>";
}

Note [S1] break and continue are the only JavaScript statements that can "jump out of" a code block. Without a label, break only exits loops or switches; with a label, it exits any code block.

🛠️ 적용 사례 (Applied in summary)

The page's own snippets are the canonical applied examples — early-exiting a for loop at i === 3, exiting switch cases, labeled breaks targeting loop1/loop2, and breaking out of a labeled list: block. No external project/commit applications found in the source.

💻 코드 패턴 (Code patterns)

Early exit from a loop:

for (let i = 0; i < 10; i++) {
  if (i === 3) { break; }
  text += "The number is " + i + "<br>";
}

Labeled break out of an outer loop:

loop1: for (let j = 1; j < 5; j++) {
  loop2: for (let i = 1; i < 5; i++) {
    if (i === 3) { break loop1; }
    text += i;
  }
}

Break out of a labeled code block:

list: {
  text += cars[0] + "<br>";
  break list;
  text += cars[2] + "<br>";
}

⚖️ 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 Loops, JavaScript For Loop, JavaScript While Loop, JavaScript Switch
• 참조 맥락: Used to terminate loops/switches early; paired with continue as the only block-jumping statements.

📚 출처 (Sources)

• [S1] W3Schools — JavaScript Break — https://www.w3schools.com/js/js_break.asp

📝 변경 이력 (Change history)

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