Primitive Data Types: Building Blocks of Data

Why This Matters: Primitive data types are the fundamental building blocks of all data in JavaScript. Understanding them is crucial for writing correct code and predicting how your variables will behave.

In JavaScript, every value has a data type. Data types categorize values, determining what kind of operations can be performed on them. JavaScript has a set of built-in data types, broadly categorized into primitives and objects.

Primitive data types are the most fundamental and are immutable (meaning their value cannot be changed after creation). When you perform an operation on a primitive, you always get a new primitive value, rather than modifying the original.

There are seven primitive data types in JavaScript:

1. String
2. Number
3. Boolean
4. null
5. undefined
6. Symbol (introduced in ES6)
7. BigInt (introduced in ES2020)

Let's explore each of them.

---

1. String

A String represents textual data. It is a sequence of characters.

Declaration: Strings can be declared using:

• Single quotes: 'Hello World'
• Double quotes: "Hello World"
• Backticks (template literals): `Hello World` (useful for embedding variables and multi-line strings, covered more in ES6+ features).

Practice: Working with Strings

Experiment with different ways to declare strings. Try to change a character in a string and observe the output to understand immutability.

---

2. Number

The Number type represents both integer and floating-point (decimal) numbers.

Practice: Exploring Numbers and Special Values

Declare different types of numbers and observe JavaScript's special numeric values like Infinity and NaN.

---

3. Boolean

The Boolean type represents a logical entity and can only have two values: true or false. It's fundamental for control flow and decision-making in your code.

Practice: Boolean Values

Declare boolean variables directly and by using comparison operations.

---

4. null

null is a special primitive value that represents the intentional absence of any object value. It indicates that a variable has been explicitly assigned "no value" or "nothing."

Key points:

• It is a primitive value.
• Its typeof operator returns 'object'. This is a long-standing bug in JavaScript that cannot be fixed without breaking existing code. Treat null as a primitive despite this typeof behavior.

Practice: Understanding null

Declare a variable and explicitly set it to null. Observe its value and typeof result.

---

5. undefined

undefined is a primitive value that indicates a variable has been declared but not yet assigned a value. It also signifies the absence of a value for function arguments that were not provided or missing object properties.

Key points:

• It is a primitive value.
• Its typeof operator returns 'undefined'.

Practice: Understanding undefined

Declare variables without assigning values, access non-existent object properties, and call functions without required arguments to see undefined in action.

---

6. Symbol (ES6)

A Symbol is a unique and immutable primitive value. It's primarily used to create unique object property keys to avoid name collisions.

Declaration: Created by calling the Symbol() function.

Practice: Using Symbol for Unique Keys

Create symbols and use them as object property keys to understand their unique nature.

---

7. BigInt (ES2020)

BigInt is a primitive data type that can represent integers with arbitrary precision (numbers larger than 2^53 - 1 or smaller than -(2^53 - 1), which is the maximum/minimum range for standard Number types).

Declaration: Created by calling the BigInt() constructor with a string or number.

Practice: Working with BigInt

Explore how to declare and perform operations with BigInt. Pay attention to the rule about not mixing BigInt with Number types directly.

---

Exercise: Exploring All Primitives

In the editor below, complete the following tasks. Use console.log() to display the value and typeof each variable after declaration.