Classes

Learn how to create classes and use inheritance to minimize redundancy in your code.

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Key Concepts

Review core concepts you need to learn to master this subject

Static Methods

Class

Class Constructor

Class Methods

extends

Static Methods

class Dog {
  constructor(name) {
    this._name = name;  
  }
  
  introduce() { 
    console.log('This is ' + this._name + ' !');  
  }
  
  // A static method
  static bark() {
    console.log('Woof!');  
  }
}

const myDog = new Dog('Buster');
myDog.introduce();

// Calling the static method
Dog.bark();

Within a JavaScript class, the static keyword defines a static method for a class. Static methods are not called on individual instances of the class, but are called on the class itself. Therefore, they tend to be general (utility) methods.

Classes

Lesson 1 of 1

1
Introduction to Classes
JavaScript is an object-oriented programming (OOP) language we can use to model real-world items. In this lesson, you will learn how to make classes. Classes are a tool that developers use to q…
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2
Constructor
In the last exercise, you created a class called Dog, and used it to produce a Dog object. Although you may see similarities between class and object syntax, there is one important method that se…
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3
Instance
Now, we’re ready to create class instances. An instance is an object that contains the property names and methods of a class, but with unique property values. Let’s look at our Dog class example….
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4
Methods
At this point, we have a Dog class that spins up objects with name and behavior properties. Below, we will add getters and a method to bring our class to life. Class method and getter syntax is t…
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5
Method Calls
Finally, let’s use our new methods to access and manipulate data from Dog instances. class Dog { constructor(name) { this._name = name; this._behavior = 0; } get name() { re…
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6
Inheritance I
Imagine our doggy daycare is so successful that we decide to expand the business and open a kitty daycare. Before the daycare opens, we need to create a Cat class so we can quickly generate Cat in…
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7
Inheritance II
In the last exercise, we created a parent class named Animal for two child classes named Cat and Dog. The Animal class below contains the shared properties and methods of Cat and Dog. class Anima…
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8
Inheritance III
We’ve abstracted the shared properties and methods of our Cat and Dog classes into a parent class called Animal (See below). class Animal { constructor(name) { this._name = name; this._b…
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9
Inheritance IV
Now that we know how to create an object that inherits properties from a parent class let’s turn our attention to methods. When we call extends in a class declaration, all of the parent methods ar…
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10
Inheritance V
In addition to the inherited features, child classes can contain their own properties, getters, setters, and methods. Below, we will add a usesLitter getter. The syntax for creating getters, sett…
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11
Static Methods
Sometimes you will want a class to have methods that aren’t available in individual instances, but that you can call directly from the class. Take the Date class, for example — you can both…
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12
Review: Classes
Way to go! Let’s review what you learned. - Classes are templates for objects. - Javascript calls a constructor method when we create a new instance of a class. - Inheritance is when we cre…
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