Objects

Introduction

• Object in JavaScript is a type of variable.
• Object represents a real world things[entities].
• for eg. car is an object, a computer is a object, etc.
• object stores key and value pair
• objects can be created mainly in two ways: Literal way and constructor way.

Literal Way of Creating an Object

•  eg. let customer={custName:"Harry", custAddress:"TKP"};

• customer is an object name, custName is a key where Harry is the value of custName, similarly, custAddress is a key name and TKP is the value of that key custAddress.

• we can simply define only. Later we can assign value to the object.

•   e.g let customer={}; // It is called literal way of creating obj.

• And then objName.keyName="<value>";

• To access objects : objName.keyName;
• eg. alert(customer.custName);

<script>

        let customer={custName:"Harry", custAddress:"TKP"};

        console.log("Name: "+ customer.custName +", Address: "+customer.custAddress);

        let car = {

            name:"Suzuki",

            model:"SZ123",

            color:"Black",

        };

        console.log(`Car Name : ${car.name}`); 

        // or we can create object in different way. First create a empty obj and

            then push the key-values.

        let person = {};

        person.name="Harry";

    </script>

Constructor ways of creating an object

- The another method of creating an object is using 'new' keyword with object().

- To create an object, first we need a constructor funtion.

- let's understand through an example:

<script>

        function account(){

            this.id="101";

            this.accHolder="Maxx";

            this.balance="10000";

            this.status = function status(){

                alert("Active");

            }

        }

        let x = new account();  // creating an instance of account. This is the 

// construction way of creating an object.

        x.status();

        console.log(x); // x is here an objec, 

//account {id: "101", accHolder: "Maxx", balance: "10000", status: ƒ}

        console.log("ID: "+ x.id);   

        console.log("Name: "+ this.accHolder);   // here accHolder is not in 

//lexical scope Name: undefined

    </script>

In the above code, account() is a constructor function we've

created that holds some variables and function status() is a

closure function.

we can create more objects like x. eg

let x1 = new account();

let x2 = new account();