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_Date_Set.md

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+---
+id: javascript-date-set-methods
+title: "JavaScript Date Set Methods"
+category: "Frontend"
+status: "draft"
+verification_status: "conceptual"
+canonical_id: ""
+aliases: ["Date setters", "setFullYear", "setMonth", "setDate", "setHours", "setTime", "date comparison"]
+duplicate_of: ""
+source_trust_level: "B"
+confidence_score: 0.9
+created_at: 2026-06-23
+updated_at: 2026-06-23
+review_reason: ""
+merge_history: []
+tags: ["javascript", "js", "web", "frontend", "w3schools", "date", "setter"]
+raw_sources: ["https://www.w3schools.com/js/js_date_methods_set.asp"]
+applied_in: []
+github_commit: ""
+---
+
+# [[JavaScript Date Set Methods]]
+
+## 🎯 한 줄 통찰 (One-line insight)
+Date Set methods write a part of a `Date` object — year, month, day, hour, minute, second, millisecond, or the raw timestamp — and several accept cascading parameters so multiple parts can be set in one call. [S1]
+
+## 🧠 핵심 개념 (Core concepts)
+- **Set Date methods set a part of a date.** [S1]
+- **Months count from 0 to 11** — January is 0, December is 11. [S1]
+- **Cascading parameters** — `setFullYear()` can also take month and day; `setHours()` can also take minutes and seconds, letting you set several fields at once. [S1]
+- **Arithmetic via get + set** — combine a getter with a setter (`d.setDate(d.getDate() + 50)`) to shift a date; boundary crossings into the next month/year adjust automatically. [S1]
+- **Dates are comparable** — relational operators (`>`, `<`) compare two `Date` objects directly. [S1]
+
+## 🧩 추출된 패턴 (Extracted patterns)
+- **Add-to-existing-field** — read a field, add to it, set it back: `d.setDate(d.getDate() + 50)`. [S1]
+- **Build a target date then compare** — create a date, set its fields to a future point, then test with `if (someday > today)`. [S1]
+- **One-call multi-field set** — pass extra arguments to a single setter instead of calling several setters. [S1]
+
+## 📖 세부 내용 (Details)
+**setFullYear() — set the year (yyyy)** [S1]
+```javascript
+const d = new Date("January 01, 2025");
+d.setFullYear(2020);
+```
+`setFullYear()` can optionally set the month and day as well: [S1]
+```javascript
+const d = new Date("January 01, 2025");
+d.setFullYear(2020, 11, 3);
+```
+
+**setMonth() — set the month (0-11)** [S1]
+```javascript
+const d = new Date("January 01, 2025");
+d.setMonth(11);
+```
+
+**setDate() — set the day as a number (1-31)** [S1]
+```javascript
+const d = new Date("January 01, 2025");
+d.setDate(15);
+```
+`setDate()` can also be used to add days to a date: [S1]
+```javascript
+const d = new Date("January 01, 2025");
+d.setDate(d.getDate() + 50);
+```
+
+**setHours() — set the hour (0-23)** [S1]
+```javascript
+const d = new Date("January 01, 2025");
+d.setHours(22);
+```
+`setHours()` can also set minutes and seconds: [S1]
+```javascript
+const d = new Date("January 01, 2025");
+d.setHours(22, 10, 20);
+```
+
+**setMinutes() — set the minutes (0-59)** [S1]
+```javascript
+const d = new Date("January 01, 2025");
+d.setMinutes(30);
+```
+
+**setSeconds() — set the seconds (0-59)** [S1]
+```javascript
+const d = new Date("January 01, 2025");
+d.setSeconds(30);
+```
+
+**Compare Dates** — dates can easily be compared. The example sets a future date and compares it to today: [S1]
+```javascript
+let text = "";
+const today = new Date();
+const someday = new Date();
+someday.setFullYear(2100, 0, 14);
+
+if (someday > today) {
+  text = "Today is before January 14, 2100.";
+} else {
+  text = "Today is after January 14, 2100.";
+}
+```
+
+**Set Date Methods** [S1]
+
+| Method | Description |
+|--------|-------------|
+| setDate() | Set the day as a number (1-31) |
+| setFullYear() | Set the year (yyyy) |
+| setHours() | Set the hour (0-23) |
+| setMilliseconds() | Set the milliseconds (0-999) |
+| setMinutes() | Set the minutes (0-59) |
+| setMonth() | Set the month (0-11) |
+| setSeconds() | Set the seconds (0-59) |
+| setTime() | Set the time (milliseconds since January 1, 1970) |
+
+**Note:** JavaScript counts months from 0 to 11. January is 0. December is 11. [S1]
+
+## 🛠️ 적용 사례 (Applied in summary)
+The page's own snippets are the canonical applied examples — setting individual fields on a parsed date, adding 50 days via `setDate(d.getDate() + 50)`, and building a future date to compare against today. No external project/commit applications found in the source.
+
+## 💻 코드 패턴 (Code patterns)
+Shift a date forward by N days (language: JavaScript):
+```javascript
+const d = new Date("January 01, 2025");
+d.setDate(d.getDate() + 50);
+```
+Set multiple fields in one call:
+```javascript
+const d = new Date("January 01, 2025");
+d.setHours(22, 10, 20);
+```
+
+## ⚖️ 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:** 0.90
+- **중복 검사 결과:** 신규 생성 (New discovery)
+
+## 🔗 지식 그래프 (Knowledge Graph)
+- **상위/루트:** [[JavaScript Tutorial]]
+- **관련 개념:** [[JavaScript Date Get Methods]], [[JavaScript Date Methods]], [[JavaScript Dates]]
+- **참조 맥락:** Used whenever mutating a Date object — adjusting fields, doing date arithmetic, or building target dates for comparison.
+
+## 📚 출처 (Sources)
+- [S1] W3Schools — JavaScript Date Set Methods — https://www.w3schools.com/js/js_date_methods_set.asp
+
+## 📝 변경 이력 (Change history)
+- 2026-06-23: Initial draft synthesized from the W3Schools "JavaScript Date Set Methods" page (Astra wiki-curation, P-Reinforce v3.1 format).