Data Types in Javascript

Javascript has several built-in data types that represent different values, which are classified into two categories: primitive data types and reference data types.

Primitive data types are immutable and it has 6 primitive data types such as number, string, boolean, undefined, null, and symbol.

Reference data types are mutable and it has 3 reference data types such as object, array, and function.

Primitive Data Types:

Primitive data types are immutable data types and stored directly in memory. They are accessed by value.

Number:

Represents numeric values. It can be integers or floating-point numbers.

Example:

let age = 35;
let price = 69.99;

String:

Represents sequences of characters and data enclosed within single (''), double (" "), or backticks (``) quotes.

Example:

let username = "Alice";

Boolean:

Represents a logical value, either true or false.

Example:

let isStudent = true;

Null & Undefined:

Null: Represents the intentional absence of any object value.

Undefined: Represents a variable that has been declared but not assigned a value.

Example:

// undefined variable
let undefinedValue;

// undefined variable
let undefinedVariable = undefined;

// null value
let nullValue = null;

Symbol (ES6 and later):

Represents a unique identifier.

Example:

let uniqueID = Symbol("id");

Reference Data Types:

Reference data types are mutable and stored as references to memory locations. They are accessed by reference.

Object Data Type:

It represents a collection of key-value pairs and is used for more complex data structures.

Example:

let person = {
  name: "Alice",
  age: 35,
  isStudent: false
};

Array:

It represents a collection of elements, indexed by integers, starting from 0.

Example:

let marks = [55, 60, 77, 80, 99, 90];

 // Accessing value of first element in `marks` array
console.log(marks[0]) // Output: 55

Function:

it represents executable code that can be invoked.

Example:

const multiply = function(a, b) {
    return a * b;
};

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