Javascript Object

Working with object in Javascript

Working with object in Javascript¶

JavaScript is designed on a simple object-based paradigm.
An object is a collection of properties, and a property is an association between a name (or key) and a value.
A property's value can be a function, in which case the property is known as a method.
We use javascript objects for representing real world objects like person, car, bus, etc.

creating an object in javascript¶

To create an object with properties, we you use the key:value within the curly braces. For example, the following creates a new person object:

syntax¶

let obj1 = {key: val}
// or
let obj2 = new Object()
obj2.key = val

create a person object¶

For a person object we have simple attributes firstName, lastName

let john = {
    firstName: "John",
    lastName: "Doe",
}

let anji = new Object()
    anji.firstName = "Anji"
    anji.lastName = "Batta"

We have created two objects in the above code. 1. john and 2. anji

reading data from javascript object¶

We can do this in 2 ways
dot notation
square backet notation

let john = {
    firstName: "John",
    lastName: "Doe",
}

let firstName = john["firstName"];
let lastName = john.lastName;
console.log(firstName);
// John
console.log(lastName);
// Doe

about javascript objects¶

Objects are the foundation of JavaScript and permeate its every aspect.
Almost everything in JavaScript is an object.
In fact, only six things are not objects. They are — null,undefined, strings, numbers, boolean, and symbols. These are called primitive values or primitive types.
Anything that is not a primitive value is an Object.
That includes arrays, functions, constructors, and objects themselves.

using functions with objects¶

we can use functions as a keys in javascript object. but, we call it as methods.
let's add fullName and greeting methods to person object.

let john = {
    firstName: "John",
    lastName: "Doe",
    fullName: function(){
        return this.firstName + " " + this.lastName;
    },
    greeting: function(){
        console.log("Hello " + this.fullName())
    }
}

console.log(john.greeting())
// Hello John Doe

Reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object