Posted By
Bajarangi soft ,
Posted On 09-10-2020
ECMAScript 2015
ES6, also known as ECMAScript2015, introduced classes.
Class Definition
Use the keyword class to create a class, and always add the constructor() method.
The constructor method is called each time the class object is initialized.
Example A simple class definition for a class named "Car":
class Car {
constructor(brand) {
this.carname = brand;
}
}
Now you can create objects using the Car class:
<script>
class Car {
constructor(brand) {
this.carname = brand;
}
}
mycar = new Car("Ford");
document.getElementById("demo").innerHTML = mycar.carname;
</script>
Methods
The constructor method is special, it is where you initialize properties, it is called automatically when a class is initiated, and it has to have the exact name "constructor", in fact, if you do not have a constructor method, JavaScript will add an invisible and empty constructor method.
You are also free to make your own methods, the syntax should be familiar:
<script>
class Car {
constructor(brand) {
this.carname = brand;
}
present() {
return "I have a " + this.carname;
}
}
mycar = new Car("Ford");
document.getElementById("demo").innerHTML = mycar.present();
</script>
As you can see in the example above, you call the method by referring to the object's method name followed by parentheses (any parameters would go inside the parentheses).
<script>
class Car {
constructor(brand) {
this.carname = brand;
}
present(x) {
return x + ", I have a " + this.carname;
}
}
mycar = new Car("Ford");
document.getElementById("demo").innerHTML = mycar.present("Hello");
</script>
Complete Code For Defining Class In Java Script
<!DOCTYPE html>
<html>
<head>
<title>Class In Java Script</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css">
</head>
<body>
<div class="container">
<br>
<div class="text-center">
<h1 id="color" style="color: tomato">Class In Java Script</h1>
</div>
<div class="well">
<h2 id="demo1"></h2>
<h2 id="demo2"></h2>
<h2 id="demo3"></h2>
<script>
class Car {
constructor(brand) {
this.carname = brand;
}
present() {
return "I have a " + this.carname;
}
}
mycar = new Car("Ford");
document.getElementById("demo1").innerHTML = mycar.carname;
document.getElementById("demo2").innerHTML = mycar.present();
document.getElementById("demo3").innerHTML = mycar.present("Hello");
</script>
</div>
</div>
</body>
</html>