QA Peddia

In JavaScript, an object is a data structure that allows you to store collections of data and more complex entities. Objects are key-value pairs, where each key (also called a property) is associated with a value. The values can be of any data type, including other objects and functions.

Creating Objects

Object Literals

The most common way to create an object is by using an object literal:

let person = {
 
name: "John",
age: 30, 
isStudent: false, 

greet: function() { 

console.log("Hello, my name is " + this.name); 
}
};

Using the new Object() Syntax

Another way to create an object is by using the Object constructor:

let person = new Object(); 

person.name = "John"
person.age = 30
person.isStudent = false

person.greet: function() {
console.log("Hello, my name is " + this.name); 
}

Object of a class

We can also create object of a class and we have seen that example in our last session

class Person {
  
  }

let person = new Person();

person.name = 'John';
person.age = 30;

console.log(person.name);
console.log(person.age)

Object of a function

We can also create object of a function because there was no concept of class in the earlier version of javascript. ES6 version of javascript introduced classes.

function person() {
  
  }

let p = new person();

p.name = 'John';
p.age = 30;

console.log(p.name);
console.log(p.age)

Accessing Object

console.log(person)

Accessing Objects using Dot Notation

console.log(person.name)
console.log(person.age)
console.log(person.isStudent)

Accessing Objects using Bracket Notation

console.log(person["name"])
console.log(person["age"])
console.log(person["isStudent"])

Accessing a function inside an object

person.greet()

Accessing the keys, values and entries of an object

console.log(Object.keys(person))
console.log(Object.values(person))
console.log(Object.entries(person));

Modifying Properties

person.name = "Jack"
person["age"] = 31

Adding Properties

person.address = "123 Main Street"

Deleting Properties

delete person.isStudent;

for in loop

for (let key in person) {
  console.log(key + ": " + person[key]);
}