JS Variables

Variables are named containers that store values you can reuse throughout your program. JavaScript gives you three keywords to declare them.

Keyword	Reassignable	Scope	Use When
const	❌ No	Block	Value won’t change (recommended default)
let	✅ Yes	Block	Value will change
var	✅ Yes	Function	Old code — avoid in modern JS

Try It — Variables in Action

Variable Naming Rules

• Must start with a letter, $, or _
• Can contain letters, digits, $, _
• Case sensitive — name ≠ Name
• Cannot be a reserved keyword (let, if, return, etc.)

Tip: Good variable names describe what the value means: userName, totalPrice, isLoggedIn. Avoid single letters like x or vague names like data.