Javascript data types with examples

Javascript data types with examples

In this chapter, you will learn about javascript data types with examples. Let’s look at the fundamental concept of variables. Basically variables are a fundamental concept of all programming languages. Variable is like a storage box in which we can store a value in order to use it whenever we need in functions. Let’s see what are the different data types are available in javascript.

Javascript data types can be categorised into 2 categories

1. Primitives values
2. Non Primitives values

Primitives values:
There are 7 different data types that are primitives in the latest ECMAScript standard and they are

1.  Number: A data type represents floating-point numbers, for decimals and integers
2.  String: A data type represents a sequence of characters used for text.
3.  Boolean: A data type represents true or false
4.  Undefined: A data type variable that does not have a value yet
5.  Null: A data type variable that notifies variable points to none
6.  BigInt: A data type represents large integers even beyond the safe integer limit for Numbers.
7.  Symbol: A Symbol is a unique and immutable primitive value

Non Primitives values:
All objects such as functions, arrays and structured JSON.

Now let’s create Number data types:

const x = 1;
const y = 2.5;
const z = 2.5 + 3.5;

console.log(x);
console.log(y);
console.log(z);

// output
// 1
// 2.5
// 6

Now let’s create String data types:

const employeeName = 'Mickel';
const lastName = 'Clark';
const department = 'IT';

console.log(employeeName);
console.log(lastName);
console.log(department);

// output
// Mickel
// Clark
// IT

Now let’s create Boolean data types:

const isAdmin = new Boolean(true);
const isSubscriber = new Boolean('true');
const isCustomer = new Boolean('false');
const isBuyer = new Boolean('true');
const isActive = true;

console.info(isAdmin);
console.info(isSubscriber);
console.info(isCustomer);
console.info(isBuyer);
console.info(isActive);

// output
// Boolean {true}
// Boolean {true}
// Boolean {true}
// Boolean {true}
// true

const isAdmin = new Boolean();
const isSubscriber = new Boolean(0);
const isCustomer = new Boolean(null);
const isBuyer = new Boolean('');
const isActive = true;

console.info(isAdmin);
console.info(isSubscriber);
console.info(isCustomer);
console.info(isBuyer);
console.info(isActive);

// output
// Boolean {false}
// Boolean {false}
// Boolean {false}
// Boolean {false}
// true

Now let’s create Undefined data types:

var employeeName;
var employeeLastName;
let employeeDepartment;

console.log(employeeName);
console.log(employeeLastName);
console.log(employeeDepartment);

// output 
// undefined
// undefined
// undefined

Now let’s create Null data types:

var employeeName = null;
var employeeLastName = null;
let employeeDepartment = null;

console.log(employeeName);
console.log(employeeLastName);
console.log(employeeDepartment);

// output 
// null
// null
// null

Dynamic typing:
One thing you might have noticed that we are using the var or let for creating the strings, numbers and null. Its because javascript is a loosely typed language. Let’s see the below examples

let employeeName = 'John';
console.log(employeeName);
employeeName = 'Mickel';
console.log(employeeName);
employeeName = 'Stark';
console.log(employeeName);

// output
// John
// Mickel
// Stark