JavaScript Syntax

JavaScript syntax refers to the set of rules that define how JavaScript code must be written to be correctly understood by the browser. Learning syntax is the first step toward writing valid and bug-free JavaScript code.

Basic Structure of JavaScript Code

A JavaScript program consists of statements that are executed by the browser.

• let is a keyword to declare a variable
• "Hello, JavaScript!" is a string value
• console.log() prints output to the browser’s console

Key Syntax Rules in JavaScript

1. Statements

Each instruction in JavaScript is called a statement, and statements are usually terminated with a semicolon ;.

2. Case Sensitivity

JavaScript is case-sensitive. For example, let, Let, and LET are all different.

3. Comments

You can write comments to explain code or disable lines during testing.

4. Identifiers (Names)

Variable and function names must follow these rules:

• Must start with a letter, $, or _
• Can contain letters, digits, $, or _
• Cannot be reserved keywords (like var, function, etc.)

5. Whitespace and Line Breaks

JavaScript ignores extra spaces and newlines. They are used to improve readability.

6. Semicolons

Semicolons are used to separate JavaScript statements. They are optional in most cases, but using them is a best practice to prevent automatic semicolon insertion (ASI) errors.

Example: Simple JavaScript Script

Key Takeaways

• JavaScript syntax defines how code is structured and written
• Statements are instructions that end with a semicolon
• JavaScript is case-sensitive and uses meaningful variable names
• Comments improve code readability and help with debugging
• Use consistent indentation and spacing for clean code