2nd/10_Wiki/Topic_JavaScript/JavaScript_Date_Set.md

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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-date-set-methods	JavaScript Date Set Methods	Frontend	draft	conceptual		Date setters setFullYear setMonth setDate setHours setTime date comparison		B	0.9	2026-06-23	2026-06-23			javascript js web frontend w3schools date setter	https://www.w3schools.com/js/js_date_methods_set.asp

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]

const d = new Date("January 01, 2025");
d.setFullYear(2020);

setFullYear() can optionally set the month and day as well: [S1]

const d = new Date("January 01, 2025");
d.setFullYear(2020, 11, 3);

setMonth() — set the month (0-11) [S1]

const d = new Date("January 01, 2025");
d.setMonth(11);

setDate() — set the day as a number (1-31) [S1]

const d = new Date("January 01, 2025");
d.setDate(15);

setDate() can also be used to add days to a date: [S1]

const d = new Date("January 01, 2025");
d.setDate(d.getDate() + 50);

setHours() — set the hour (0-23) [S1]

const d = new Date("January 01, 2025");
d.setHours(22);

setHours() can also set minutes and seconds: [S1]

const d = new Date("January 01, 2025");
d.setHours(22, 10, 20);

setMinutes() — set the minutes (0-59) [S1]

const d = new Date("January 01, 2025");
d.setMinutes(30);

setSeconds() — set the seconds (0-59) [S1]

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]

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):

const d = new Date("January 01, 2025");
d.setDate(d.getDate() + 50);

Set multiple fields in one call:

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).