JavaScript Syntax

What is JavaScript Syntax?

JavaScript syntax refers to the set of rules that define how JavaScript programs are written and understood by the browser.

Just like grammar in a language, syntax tells JavaScript how to read and execute code.

 Basic Rules

1. JavaScript Statements

Each instruction is called a statement and usually ends with a semicolon (;).

2. JavaScript Variables

Variables store data. Examples:

3. JavaScript Identifiers (Names)

Names of variables, functions, etc.

Rules:

• Must start with a letter, _ or $

• Cannot start with a number

• Case-sensitive (age ≠ Age)

Example:

4. JavaScript Comments

Comments are ignored by the browser.

5. JavaScript Keywords

Keywords are reserved words (cannot be variable names):

let, var, const, if, else, function, return, class, etc.

Example:

6. JavaScript Values

Two types:

Example:

Example with Output

Output:

Case Sensitivity

JavaScript is case-sensitive:

Summary Table