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>
2026-06-23 19:21:18 +09:00
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+---
+id: javascript-date-get-methods
+title: "JavaScript Date Get Methods"
+category: "Frontend"
+status: "draft"
+verification_status: "conceptual"
+canonical_id: ""
+aliases: ["Date getters", "getFullYear", "getMonth", "getDate", "getTime", "Date.now", "getTimezoneOffset"]
+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", "getter"]
+raw_sources: ["https://www.w3schools.com/js/js_date_methods.asp"]
+applied_in: []
+github_commit: ""
+---
+
+# [[JavaScript Date Get Methods]]
+
+## 🎯 한 줄 통찰 (One-line insight)
+Date Get methods read individual parts out of a `Date` object — year, month, day, weekday, hours, minutes, seconds, milliseconds, and the underlying timestamp — with month and weekday returned as zero-based numbers. [S1]
+
+## 🧠 핵심 개념 (Core concepts)
+- **`new Date()` creates a date object** holding a date and time. Get methods then extract individual components from it. [S1]
+- **Months are zero-based** — `getMonth()` returns `0-11`, where January is 0. [S1]
+- **Weekdays are zero-based** — `getDay()` returns `0-6`, where Sunday is 0. [S1]
+- **`getTime()` returns the timestamp** — milliseconds since January 1, 1970. [S1]
+- **`Date.now()` is a static method** that returns the current milliseconds since January 1, 1970 (it is a method of `Date`, not of a date instance). [S1]
+- **`getTimezoneOffset()`** returns the difference, in minutes, between local time and UTC. UTC time is the same as GMT. [S1]
+- **`getYear()` is deprecated** — old code may use it to return a 2-digit year; do not use it. [S1]
+
+## 🧩 추출된 패턴 (Extracted patterns)
+- **Number-to-name lookup** — because `getMonth()`/`getDay()` return zero-based numbers, map them to readable names through an array indexed by that number. [S1]
+- **Hardcoded vs current date** — the same getter works on a parsed literal (`new Date("2021-03-25")`) or on the current moment (`new Date()`). [S1]
+- **Derive durations from timestamps** — divide `Date.now()` by a precomputed unit (ms per year) to estimate elapsed time. [S1]
+
+## 📖 세부 내용 (Details)
+**Creating a date object** [S1]
+```javascript
+const date = new Date();
+```
+
+**getFullYear() — year as a four digit number (yyyy)** [S1]
+```javascript
+const d = new Date("2021-03-25");
+d.getFullYear();
+```
+```javascript
+const d = new Date();
+d.getFullYear();
+```
+
+**getMonth() — month as a number (0-11)** [S1]
+```javascript
+const d = new Date("2021-03-25");
+d.getMonth();
+```
+```javascript
+const d = new Date();
+d.getMonth();
+```
+You can use an array of names to return the month as a name: [S1]
+```javascript
+const months = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
+
+const d = new Date("2021-03-25");
+let month = months[d.getMonth()];
+```
+```javascript
+const months = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
+
+const d = new Date();
+let month = months[d.getMonth()];
+```
+
+**getDate() — day as a number (1-31)** [S1]
+```javascript
+const d = new Date("2021-03-25");
+d.getDate();
+```
+```javascript
+const d = new Date();
+d.getDate();
+```
+
+**getHours() — hour (0-23)** [S1]
+```javascript
+const d = new Date("2021-03-25");
+d.getHours();
+```
+```javascript
+const d = new Date();
+d.getHours();
+```
+
+**getMinutes() — minute (0-59)** [S1]
+```javascript
+const d = new Date("2021-03-25");
+d.getMinutes();
+```
+```javascript
+const d = new Date();
+d.getMinutes();
+```
+
+**getSeconds() — second (0-59)** [S1]
+```javascript
+const d = new Date("2021-03-25");
+d.getSeconds();
+```
+```javascript
+const d = new Date();
+d.getSeconds();
+```
+
+**getMilliseconds() — millisecond (0-999)** [S1]
+```javascript
+const d = new Date("2021-03-25");
+d.getMilliseconds();
+```
+```javascript
+const d = new Date();
+d.getMilliseconds();
+```
+
+**getDay() — weekday as a number (0-6)** [S1]
+```javascript
+const d = new Date("2021-03-25");
+d.getDay();
+```
+```javascript
+const d = new Date();
+d.getDay();
+```
+You can use an array of names to return the weekday as a name: [S1]
+```javascript
+const days = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
+
+const d = new Date("2021-03-25");
+let day = days[d.getDay()];
+```
+```javascript
+const days = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
+
+const d = new Date();
+let day = days[d.getDay()];
+```
+
+**getTime() — milliseconds since January 1, 1970** [S1]
+```javascript
+const d = new Date("1970-01-01");
+d.getTime();
+```
+```javascript
+const d = new Date("2021-03-25");
+d.getTime();
+```
+```javascript
+const d = new Date();
+d.getTime();
+```
+
+**Date.now() — current milliseconds since January 1, 1970** [S1]
+```javascript
+let ms = Date.now();
+```
+Calculate the number of years since 1970: [S1]
+```javascript
+const minute = 1000 * 60;
+const hour = minute * 60;
+const day = hour * 24;
+const year = day * 365;
+
+let years = Math.round(Date.now() / year);
+```
+
+**getTimezoneOffset() — difference between local time and UTC, in minutes** [S1]
+```javascript
+let diff = d.getTimezoneOffset();
+```
+
+**Date Get Methods** [S1]
+
+| Method | Description |
+|--------|-------------|
+| getFullYear() | Get **year** as a four digit number (yyyy) |
+| getMonth() | Get **month** as a number (0-11) |
+| getDate() | Get **day** as a number (1-31) |
+| getDay() | Get **weekday** as a number (0-6) |
+| getHours() | Get **hour** (0-23) |
+| getMinutes() | Get **minute** (0-59) |
+| getSeconds() | Get **second** (0-59) |
+| getMilliseconds() | Get **millisecond** (0-999) |
+| getTime() | Get **time** (milliseconds since January 1, 1970) |
+
+**UTC Date Get Methods** — UTC time is the same as GMT. [S1]
+
+| Method | Same As | Description |
+|--------|---------|-------------|
+| getUTCDate() | getDate() | Returns the UTC date |
+| getUTCFullYear() | getFullYear() | Returns the UTC year |
+| getUTCMonth() | getMonth() | Returns the UTC month |
+| getUTCDay() | getDay() | Returns the UTC day |
+| getUTCHours() | getHours() | Returns the UTC hour |
+| getUTCMinutes() | getMinutes() | Returns the UTC minutes |
+| getUTCSeconds() | getSeconds() | Returns the UTC seconds |
+| getUTCMilliseconds() | getMilliseconds() | Returns the UTC milliseconds |
+
+## 🛠️ 적용 사례 (Applied in summary)
+The page's own snippets are the canonical applied examples — reading components off both a parsed literal date and the current date, and converting zero-based month/weekday numbers to names via lookup arrays. No external project/commit applications found in the source.
+
+## 💻 코드 패턴 (Code patterns)
+Convert a zero-based month number to a readable name (language: JavaScript):
+```javascript
+const months = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
+const d = new Date();
+let month = months[d.getMonth()];
+```
+Get the current timestamp:
+```javascript
+let ms = Date.now();
+```
+
+## ⚖️ 모순 및 업데이트 (Contradictions & updates)
+The source flags `getYear()` as deprecated and non-standard; `getFullYear()` is the standard replacement. No other contradictions found in the source. [S1]
+
+## ✅ 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 Set Methods]], [[JavaScript Date Methods]], [[JavaScript Dates]]
+- **참조 맥락:** Used whenever reading date/time parts out of a Date object for display or computation.
+
+## 📚 출처 (Sources)
+- [S1] W3Schools — JavaScript Date Get Methods — https://www.w3schools.com/js/js_date_methods.asp
+
+## 📝 변경 이력 (Change history)
+- 2026-06-23: Initial draft synthesized from the W3Schools "JavaScript Date Get Methods" page (Astra wiki-curation, P-Reinforce v3.1 format).