In this lesson, we cover variables, constants, and data types in JavaScript, which are fundamental building blocks of programming.

Variables

Variables are used to hold information during code execution. They can be created using the keywords var or let. For example:

var firstName = "John";
let lastName = "Smith";

Variables can hold single or multiple values and can be reassigned. For instance:

let age = 5;
age = 6; // age is now 6

Think of a variable as a shopping cart that holds items during your shopping trip.

Constants

Constants are defined using the keyword const and cannot be reassigned once set. For example:

const occupation = "Engineer";

If you attempt to change a constant's value, an error occurs:

occupation = "Driver"; // Error: Assignment to constant variable

Data Types

JavaScript has five primitive data types:

String: Text enclosed in quotes, e.g., "Hello"
Number: Numeric values without quotes, e.g., 25
Boolean: Represents true or false
Null: Represents no value
Undefined: Indicates a variable that has not been assigned a value

In summary, variables can hold and change values, while constants maintain a fixed value. JavaScript supports various data types for different kinds of information.