Lesson: Introduction to JavaScript – Data Types

Objective

By the end of this lesson, students will:

1. Understand the four main primitive data types in JavaScript.
2. Differentiate between strings, numbers, booleans, and null values.
3. Write and debug code using these data types effectively.

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Introduction

In JavaScript, data types are the foundation of programming. They define the kind of values a variable can hold. JavaScript includes primitive data types, which are the simplest and most fundamental forms of data.

The four primary primitive data types in JavaScript are:

1. Strings
2. Numbers
3. Booleans
4. Null

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Explanation of Primitive Data Types

1. Strings

Strings are used to represent text. They are sequences of characters wrapped in single (') or double (") quotes.

Example:

2. Numbers

Numbers represent numerical values, including both integers and decimals.

Example:

3. Booleans

Booleans represent logical states and can only be true or false.

Example:

4. Null

Null is a special keyword that represents the intentional absence of any value.

Example:

Code Example

The following code demonstrates all four primitive data types:

Exercise 1: Write Your Own Examples

Instructions

Write a program that:

1. Logs a string of your choice.
2. Logs a number of your choice.
3. Logs a boolean value.
4. Logs a null value.

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Solution

Exercise 2: Debugging Activity

Here’s a buggy code snippet. Identify and fix the errors:

Solution

Exercise 3: Advanced Challenge

1. Create variables for each primitive data type and assign them values.
2. Log the type of each variable using the typeof operator.

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Solution

Quiz

Multiple Choice Questions

1. Which of the following is a string?
   • a) "Hello"
   • b) 42
   • c) true
   • d) null
     Answer: a)
2. What does null represent in JavaScript?
   • a) A string with no characters.
   • b) A value that equals zero.
   • c) The intentional absence of any value.
   • d) A boolean value.
     Answer: c)
3. What will typeof null return in JavaScript?
   • a) null
   • b) undefined
   • c) object
   • d) boolean
     Answer: c)

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Coding Quiz

Write a program to:

1. Declare a variable for each primitive data type.
2. Log each variable and its type using typeof.

SOLUTION

Recap

• Strings are sequences of characters wrapped in quotes.
• Numbers represent numerical values.
• Booleans are logical values (true or false).
• Null represents the absence of value.