JavaScript data type

In JavaScript, a data type defines the type of value a variable can hold. JavaScript is a dynamically typed language, meaning you don't need to specify the data type when declaring a variable; it is determined automatically based on the value assigned.

Here are the main data types in JavaScript with examples:

1. Number

Represents both integer and floating-point numbers.


let age = 25;           // Integer
let price = 19.99;      // Floating-point

2. String

Represents a sequence of characters (text).


let name = "Alice";      // Using double quotes
let greeting = 'Hello';  // Using single quotes

3. Boolean

Represents a logical value: true or false.


let isStudent = true;
let isAdult = false;

4. Undefined

A variable that has been declared but not assigned a value.


let unassignedVar;
console.log(unassignedVar); // Output: undefined

5. Null

Represents an intentionally empty or non-existent value

let emptyValue = null;

6. Object

Represents a collection of properties, where each property is a key-value pair. Objects can also represent more complex data structures like arrays and functions.

let person = {
    name: "John",
    age: 30,
    isStudent: false
};

Array: A special type of object for storing ordered lists.
```
let numbers = [1, 2, 3, 4, 5];
```
Function: A block of code designed to perform a particular task.
```
function sayHello() {
    return "Hello!";
}
```

7. Symbol (ES6)

Represents a unique and immutable identifier.


let sym = Symbol('unique');

8. BigInt (ES11)

Represents integers with arbitrary precision.


let bigNumber = 1234567890123456789012345678901234567890n;

Example Code Snippet Using Different Data Types:

let age = 25;                            // Number
let name = "Alice";                      // String
let isStudent = true;                    // Boolean
let unassignedVar;                       // Undefined
let emptyValue = null;                   // Null

let person = {                           // Object
    name: "John",
    age: 30,
    isStudent: false
};

let numbers = [1, 2, 3, 4, 5];           // Array

function sayHello() {                    // Function
    return "Hello!";
}

let sym = Symbol('unique');              // Symbol

let bigNumber = 1234567890123456789012345678901234567890n; // BigInt

These are the fundamental data types in JavaScript, each serving different purposes depending on the needs of your program.