JavaScript is a flexible object-oriented language when it comes to syntax. In this article, we will see the different ways to instantiate objects in JavaScript.
Before we proceed it is important to note that JavaScript is an object-based language based on prototypes, rather than being class-based. Because of this different basis, it can be less apparent how JavaScript allows you to create hierarchies of objects and to have an inheritance of properties and their values.
Creating object with a constructor:
One of the easiest way to instantiate an object in JavaScript. Constructor is nothing but a function and with help of new keyword, constructor function allows to create multiple objects of same flavor as shown below:
function vehicle[name,maker,engine]{
this.name = name;
this.maker = maker;
this.engine = engine;
}
let car = new
vehicle['GT','BMW','1998cc'];
console.log[car.name];
console.log[car.maker];
console.log[car['engine']];
Output:
Explanation: A class in OOPs have two major components, certain parameters and few member functions. In this method we declare a function similar to a class, there are three parameters, name, maker and engine [ the this keyword is used to differentiate the name,maker,engine of the class to the name,maker,engine of the arguments that are being supplied.]. We then simple create an object obj of the vehicle, initialize it and call it’s method.
Using object literals:
Literals are smaller and simpler ways to define objects.We simple define the property and values inside curly braces as shown below:
let car = {
name : 'GT',
maker : 'BMW',
engine : '1998cc'
};
console.log[car.name];
console.log[car['maker']];
Output:
In the above code we created a simple object named car with the help of object literal,having properties like name,maker,engine.Then we make use of the property accessor methods[Dot notation,Bracket notation] to console.log the values.
Now let’s see how we can add more properties to an already defined object:
let car = {
name : 'GT',
maker : 'BMW',
engine : '1998cc'
};
car.brakesType = 'All Disc';
console.log[car];
We added new property called brakesType to the above defined car object and when we console.log the entire object we
get:
Output:
Methods can also be part of object while creation or can be added later like properties as shown below:
let car = {
name : 'GT',
maker : 'BMW',
engine : '1998cc',
start : function[]{
console.log['Starting the engine...'];
}
};
car.start[];
car.stop = function[] {
console.log['Applying Brake...'];
}
car.stop[];
Output: