Lesson 4: Variables and Data Types

Variables and Data Types

Variables are used to store data that can be referenced and manipulated in a program. In this lesson, we’ll learn how to declare variables and explore different data types in JavaScript.

1. Declaring Variables:

Use var, let, or const to declare variables.
let and const are preferred over var due to better scoping rules.

2. Variable Assignment:

Assign values to variables using the assignment operator (=).
Example:

let name = 'John';

const age = 25;

var isStudent = true;

3. Data Types:

JavaScript supports various data types, including:
- String: Text enclosed in single or double quotes.
- Number: Numeric values.
- Boolean: True or false values.
- Array: Ordered collections of values.
- Object: Collections of key-value pairs.
- Null: Represents the intentional absence of any value.
- Undefined: Variables that have been declared but not assigned a value.

Example Code:

<!DOCTYPE html>

<html>

<head>

  <title>JavaScript Variables and Data Types</title>

</head>

<body>

  <h1>Variables and Data Types</h1>

  <script>

    let name = 'Alice';

    const age = 30;

    var isStudent = false;
    console.log('Name:', name); // Output: Name: Alice

    console.log('Age:', age); // Output: Age: 30

    console.log('Is Student:', isStudent); // Output: Is Student: false
    let hobbies = ['reading', 'sports', 'music'];

    let person = {firstName: 'John', lastName: 'Doe'};

console.log('Hobbies:', hobbies); // Output: Hobbies: ["reading", "sports", "music"] console.log('Person:', person); // Output: Person: {firstName: "John", lastName: "Doe"} </script> </body> </html>

Conclusion: Understanding variables and data types is essential for managing and manipulating data in JavaScript. Practice declaring variables and using different data types to become comfortable with these fundamental concepts.

Curriculum

JavaScript Basics

Introduction to JavaScript

Starting Course

Control Flow and Functions

After Intro

Working with Data

DOM Manipulation and Events

Final Assessment

Lesson 4: Variables and Data Types

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