Primitive and Non-primitive data-types in JavaScript
Data Types: Every Variable has a data type that tells what kind of data is being stored in a variable. There are two types of data types in JavaScript namely Primitive data types and Non-primitive data types.
Primitive data types: The predefined data types provided by JavaScript language are known as primitive data types. Primitive data types are also known as in-built data types.
Non-primitive data types: The data types that are derived from primitive data types of the JavaScript language are known as non-primitive data types. It is also known as derived data types or reference data types.
There are five types of primitive data types in Javascript.
1. Number: Number data type in javascript can be used to hold decimal values as well as values without decimals.
Javascript
<script> let x = 250; let y = 40.5; console.log( "Value of x=" + x); console.log( "Value of y=" + y); </script> |
Output:

number output
2. String: The string data type in javascript represents a sequence of characters that are surrounded by single or double quotes.
Javascript
<script> let str = 'Hello All' ; let str1 = "Welcome to my new house" ; console.log( "Value of str=" + str); console.log( "Value of str1=" + str1); </script> |
Output:

string output
3. Undefined: The meaning of undefined is ‘value is not assigned’.
Javascript
<script> console.log( "Value of x=" + x); </script> |
Output:

undefined output
4. Boolean: The boolean data type can accept only two values i.e. true and false.
Javascript
<script> console.log( "value of bool=" + bool); </script> |
Output:

boolean output
5. Null: This data type can hold only one possible value that is null.
Javascript
<script> let x = null ; console.log( "Value of x=" + x); </script> |

null output
The non-primitive data types are as follows:
1. Object: 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 var obj = new Object(); // Create a user defined object var mycar = new Car();
- Using Literal notations to define an object:
// An empty object var square = {}; // Here a and b are keys and // 20 and 30 are values var circle = {a: 20, b: 30};
Example:
Javascript
<script> // Creating object with the name person let person = { firstName: "Luiza" , lastName: "Shaikh" , }; // Print the value of object on console console.log(person.firstName + " " + person.lastName); </script> |

object output
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 var a = new Array(); // Call it with single numeric argument var b = new Array(10); // Explicitly specify two or // more array elements var d = new Array(1, 2, 3, "Hello");
Example:
Javascript
<script> var a = new Array(); var b = new Array(10); var 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); </script> |
Output:

array output
JavaScript does not support two-dimensional arrays. but we can do this by creating an array of an array.
Primitive vs Non-Primitive
Primitive |
Non-Primitive |
Primitive Data types are predefined |
Non-Primitive data types are created by programmer |
Primitive Data types will have certain values |
Non-Primitive data types can be NULL |
Size depends on type on data structure |
Size are not fixed |
Examples are numbers, string |
Example are Array, Linked List |
It can start with lowercase |
It can start with uppercase |