Tuesday, March 9, 2021

What are data types in Javascript?

 A) Values in Javascript will have a type.


B) There are 8 basic data types in Javascript.


1) String


let name = 'Test';  


String in Javscript is surrounded by quotes. 

Quotes can single, double quotes.


2) Number


let n = 10;  // Number


3) Boolean


let checkName =  true;

let checkData = false;


4) "null" 


It contains only null value. 

In Javascript, null is not a reference to a non existing object or null pointer. 

It just represents empty or unknown value.


let a= null;


5) "undefined"


It also represent special type, here the variable is declared but not assigned any value as shown below,


let a;


6) bigint


Used to store integers value of arbitrary length.


bigint value is created by appending n to the end of an integer.


const = 11111111112222222223333333333344444444n;


7) object


a) object are used to store collections of data and more complex entities.


b) objects can be created using {...} with optional list of properties, a property is "key": "value" pair.


c) Creating an empty object,


let studentDetail = {};

let steudentDetail = new Object();



d) Creating an object with properties,


let studentDetail = {

"name": "Test",

"rollNo": 1,

"Full Name": "Test User"


};


e) To access the property values use dot notation or array notation in case of space in key name as shown below,


studentDetail.name  // dot notation


To access full name use array notation as it has space.


studentDetail[Full Name]   // array notation


f) Adding a value to property,


studentDetail.department = 'Computer Science';


g) We may add comma to last property as shown below.


let studentDetail = {

name: "Test",

rollNo: 1,

};


h) To access the keys use,


Object.keys(studentDetail)


i) Use JSON.stringify to convert object to string


var jsonStrng= JSON.stringify(studentDetail);


console.log(jsonStrng);


"{"name":"Test","rollNo":1,"Full Name":"Test User"}"


j) Use JSON.parse to convert string to object


Object = JSON.parse(jsonStrng);


{name: "Test", rollNo: 1, Full Name: "Test User"}



k) The below are also different kinds of object in Javascript,


Array

Date

Error


8) symbol

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