Lesson 1: JavaScript Syntax Overview

Learning Objectives

By the end of this lesson, learners will:

• Understand what JavaScript syntax is and why it matters
• Be able to write basic JavaScript statements correctly
• Learn about semicolons, line breaks, case sensitivity, indentation, and comments
• Gain confidence in writing and organizing their first JavaScript code snippets

What Is Syntax in Programming?

Syntax is like grammar for a programming language.
It’s a set of rules and structure that determines how code must be written so the computer can understand and execute it.

Just like a sentence in English has a subject and verb, JavaScript statements must follow certain rules.

The Building Blocks of JavaScript Syntax

1. Statements

A statement is a single instruction in JavaScript — like a sentence in English.

📌 Example:

let message = "Hello, Codevisionz!";

Here, we’re telling JavaScript to:

• Create a variable named message
• Assign the string "Hello, Codevisionz!" to it

2. Semicolons (;)

Semicolons are used to end a statement in JavaScript.

📌 Example:

let x = 5;
let y = 10;
console.log(x + y);

🔹 JavaScript usually allows omitting semicolons, but it’s good practice to use them to avoid unexpected behavior.

3. Case Sensitivity

JavaScript is case-sensitive — this means:

let name = "Alice";
let Name = "Bob";

These are two different variables!

📌 Best Practice: Stick to camelCase for variables (like userName, totalAmount).

4. Curly Braces {} for Code Blocks

Curly braces are used to group multiple statements into one block — like in functions, loops, or conditionals.

📌 Example:

if (true) {
  console.log("This will run!");
}

Everything inside {} is treated as a single block of code.

5. Indentation and Formatting

While not required by JavaScript, indentation (spacing code to show structure) is critical for readability.

📌 Example:

if (score > 50) {
  console.log("You passed!");
} else {
  console.log("Try again.");
}

Use 2 or 4 spaces consistently to indent blocks.

6. Comments

Comments let you explain your code. JavaScript ignores comments when running the code.

Single-line comment:

// This is a comment

Multi-line comment:

/*
  This is a
  multi-line comment
*/

✅ Use comments to:

• Explain complex logic
• Describe what your code is doing
• Temporarily disable code (for testing)

Practice Exercise (Try in Browser Console)

// This is a simple calculation
let a = 5;
let b = 3;
let result = a + b;

console.log("The result is: " + result); // Output: The result is: 8

Common Beginner Mistakes

Summary Table