2nd/10_Wiki/Topics/Domain_Programming/Topic_JavaScript/JavaScript_Syntax.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-syntax	JavaScript Syntax	Frontend	draft	conceptual		JS syntax literals identifiers case sensitivity camelCase		B	0.88	2026-06-23	2026-06-23			javascript js web frontend w3schools syntax identifiers	https://www.w3schools.com/js/js_syntax.asp

JavaScript Syntax

🎯 한 줄 통찰 (One-line insight)

JavaScript syntax is the set of rules for how programs are constructed — built from values (literals and variables), keywords, operators, expressions, and identifiers, all of which are case-sensitive. [S1]

🧠 핵심 개념 (Core concepts)

• Syntax = construction rules — JavaScript syntax is the set of rules for how JavaScript programs are constructed. [S1]
• Two kinds of values — fixed values (literals) and variable values (variables). [S1]
• Literals — numbers are written with or without decimals; strings are text written within double or single quotes. [S1]
• Keywords create variables — the let and const keywords are used to create variables; keywords are case-sensitive. [S1]
• Variables store data — variables are containers for storing data values and must have unique names. [S1]
• JavaScript is case-sensitive — lastName and lastname are two different variables. [S1]

🧩 추출된 패턴 (Extracted patterns)

• Declare → assign → compute — declare variables with let/const, assign values, then combine them in expressions. [S1]
• Lower camelCase naming — hyphens are not allowed; underscores and PascalCase are possible, but JavaScript programmers tend to use lower camelCase. [S1]
• Identifier rules — start with a letter, _, or $; later characters may include digits; never a reserved keyword; case-sensitive. [S1]

📖 세부 내용 (Details)

JavaScript Syntax — JavaScript syntax is the rules for how JavaScript programs are constructed. A basic program declares variables, computes values, and may contain comments: [S1]

// How to Declare variables:
let x = 5;
let y = 6;

// How to Compute values:
let z = x + y;

// I am a Comment. I do Nothing

JavaScript Values — The JavaScript syntax defines two types of values: fixed values (literals) and variable values (variables). [S1]

JavaScript Literals — Numbers are written with or without decimals: [S1]

10.50

1001

Strings are text, written within double or single quotes: [S1]

"John Doe"

'John Doe'

JavaScript Keywords — JavaScript keywords are used to identify actions to be performed. The let and const keywords tell the browser to create variables: [S1]

let x = 5;

const fname = "John";

JavaScript Variables — In a programming language, variables are used to store data values. JavaScript uses the keywords var, let, and const to declare variables. An equal sign (=) is used to assign values to variables: [S1]

// Define x as a variable
let x;

// Assign the value 6 to x
x = 6;

JavaScript Operators — JavaScript uses arithmetic operators (+, -, *, /) to compute values, and an assignment operator (=) to assign values to variables: [S1]

let x = 5;
let y = 6;
let sum = x + y;

JavaScript Expressions — An expression is a combination of values, variables, and operators which computes to a value. The computation is called an evaluation. Expressions can also contain variable values, and the values can be of various types, such as numbers and strings: [S1]

5 * 10

(5 + 6) * 10

x * 10

"John" + " " + "Doe"

JavaScript Identifiers / Names — Identifiers are JavaScript names, used to name variables, keywords, and functions. The rules for legal names are: [S1]

• Names can contain letters, digits, underscores, and dollar signs.
• Names must begin with a letter, $, or _.
• Names are case-sensitive.
• Reserved words (like JavaScript keywords) cannot be used as names.

JavaScript is Case Sensitive — All JavaScript identifiers are case-sensitive. The variables lastName and lastname are two different variables: [S1]

let lastName = "Doe";
let lastname = "Peterson";

JavaScript and Camel Case — Historically, programmers have used different ways of joining multiple words into one variable name: hyphens (not allowed in JavaScript — they are reserved for subtractions), underscores, Upper Camel Case (Pascal Case), and Lower Camel Case. JavaScript programmers tend to use camel case that starts with a lowercase letter. [S1]

🛠️ 적용 사례 (Applied in summary)

The page's own snippets are the canonical applied examples — declaring with let/const, computing x + y, evaluating expressions like (5 + 6) * 10, and the case-sensitive lastName/lastname pair. No external project/commit applications found in the source.

💻 코드 패턴 (Code patterns)

Declare, assign, compute:

let x = 5;
let y = 6;
let z = x + y;

String concatenation expression:

"John" + " " + "Doe"

⚖️ 비교 및 선택 기준 (Comparison & decision criteria)

For joining multiple words into one identifier, the source presents the options and JavaScript's convention: [S1]

Style	Example	JavaScript stance
Hyphens	first-name	Not allowed (reserved for subtraction)
Underscores	first_name	Possible
Upper Camel Case (Pascal)	FirstName	Possible
Lower Camel Case	firstName	Preferred convention by JavaScript programmers

⚖️ 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: 0.88
• 중복 검사 결과: 신규 생성 (New discovery)

🔗 지식 그래프 (Knowledge Graph)

• 상위/루트: JavaScript Tutorial
• 관련 개념: JavaScript Statements, JavaScript Variables, JavaScript Comments
• 참조 맥락: The grammar layer underpinning every other JavaScript topic.

📚 출처 (Sources)

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

📝 변경 이력 (Change history)

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