Variables, Data Types & Operators

Every program needs to remember values and do something with them: a name, a price, whether a checkbox is checked. This module covers variables, the types of values JavaScript works with, and the operators you’ll use to combine and compare them.

Why This Matters

Variables and data types are the raw material every later module builds on. Functions take them as input, arrays and objects store collections of them, and control flow decides what happens based on them. Get comfortable here first.

What You’ll Learn

• Declaring variables with let and const (and why var is mostly avoided in modern code)
• JavaScript’s core data types, and how to check the type of any value
• Operators: arithmetic, comparison, logical, and assignment
• Type conversion, and the difference between doing it on purpose and by accident
• Basic input and output, comments, coding conventions, and strict mode

Outcome

By the end of this module, you’ll be able to declare variables, recognize what type any value is, and write expressions using JavaScript’s common operators.

Let’s get started.