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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