What are they primitive data types and non-primitive data types and difference?

Primitive and Non-primitive data-types in JavaScript.

Variables hold values, and every value has a specific data type that defines the kind of information it holds. These data types are broadly categorized into two groups: Primitive Data Types and Non-Primitive Data Types. Let us discuss it one by one.

1. Primitive Data Types:

Primitive data types are the built-in data types provided by JavaScript. They represent single values and are not mutable. JavaScript supports the following primitive data types:

1.1 Number:
Number data type in JavaScript can be used to hold decimal values as well as values without decimals.

Example:

let x = 250;
let y = 40.5;
console.log("Value of x=" + x);
console.log("Value of y=" + y);

Output
Value of x=250
Value of y=40.5

1.2 String:

The string data type in JavaScript represents a sequence of characters that are surrounded by single or double quotes.

Example:

let str = 'Hello All';
let str1 = "Welcome to my new house";
console.log("Value of str=" + str);
console.log("Value of str1=" + str1);

Output

Value of str=Hello All
Value of str1=Welcome to my new house

1.3 Undefined:

This means that a variable has been declared but has not been assigned a value, or it has been explicitly set to the value undefined.

Example:

let x;
console.log(x); // Outputs: undefined

Output:

Screenshot-(6)
undefined output

1.4 Boolean:
The boolean data type can accept only two values i.e. true and false.

Example:

let x;
console.log(x); // Outputs: undefined

Output:

Click to enlarge
boolean output

1.5 Null:

This data type can hold only one possible value that is null.

Example:

let x = null;
console.log("Value of x=" + x);

Output

Value of x=null

1.6 BigInt:

BigInt data type can represent numbers greater than 253-1 which helps to perform operations on large numbers. The number is specified by writing 'n' at the end of the value

Example: Below is an example.

let bigNum = 123422222222222222222222222222222222222n
console.log(bigNum)

Output

123422222222222222222222222222222222222n

1.7 Symbol:

Symbol data type is used to create objects which will always be unique. these objects can be created using Symbol constructor.

Example:

let sym = Symbol("Hello")
console.log(typeof(sym));
console.log(sym);

Output

symbol
Symbol(Hello)

1. Non-primitive Data Types:

Non-primitive data types, also known as reference types, are objects and derived data types. They can store collections of values or more complex entities. The two key non-primitive data types in JavaScript are:

2.1 Object:

An object in Javascript is an entity having properties and methods. Everything is an object in javascript.

How to create an object in javascript:

Using Constructor Function to define an object:

// Create an empty generic object
let obj = new Object();

// Create a user defined object

let mycar = new Car();
Using Literal notations to define an object:

// An empty object
let square = {};

// Here a and b are keys and
// 20 and 30 are values
let circle = {a: 20, b: 30};

Example:

// Creating object with the name person
let person = {
firstName: "MS",
lastName: "Praveen",
};
​
// Print the value of object on console
console.log(person.firstName
+ " " + person.lastName);

Output
MS Praveen

2.2 Array:

With the help of an array, we can store more than one element under a single name.

Ways to declare a single-dimensional array:

// Call it with no arguments
let a = new Array();

// Call it with single numeric argument
let b = new Array(10);

// Explicitly specify two or
// more array elements
let d = new Array(1, 2, 3, "Hello");

Example:

let a = new Array();
let b = new Array(10);
let d = new Array(1, 2, 3, "Hello");
console.log("value of a=" + a);
console.log("value of b" + b);
console.log("value of d=" + d);

Output

value of a=
value of b,,,,,,,,,
value of d=1,2,3,Hello

Note: JavaScript does not support two-dimensional arrays. but we can do this by creating an array of an array.

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Primitive data types:

Primitive Data types are predefined.

Primitive Data types will have certain values.

Size depends on the type of data structure.

Examples are numbers and strings.

It can start with a lowercase.

Non-primitive data types:

Non-Primitive data types are created by the programmer
Primitive Data types will have certain values.

Non-Primitive data types can be NULL.

Size is not fixed.

Examples are Array and Linked List.

It can start with uppercase.

Reference website geeksforgeeks.org