Javascript Inheritance

Javascript Inheritance Definition: The Basics

As you delve into JavaScript coding, you will encounter a concept known as Javascript Inheritance. There are a few things to note when we talk about JavaScript Inheritance:

• JavaScript uses prototypes instead of classes for inheritance.
• JavaScript Inheritance is chiefly made possible via the prototype chain.

Javascript Inheritance is about objects and properties. To put it simply, when you try to access a certain property of an object, JavaScript will first look to see if it's defined on the current object. If not, it will look on the object's [prototype].

let parent = {
  name: 'Parent',
  age: 50,
  greet: function() {
    console.log('Hello');
  }
};
  
let child = Object.create(parent);

In the code snippet above, the child object inherits properties and methods from the parent object.

The role of Javascript Inheritance in Object-oriented Programming

Object-oriented Programming, also known as OOP, is a popular coding methodology that is based on the concept of 'objects'. In this structure, JavaScript Inheritance plays an invaluable role.

Insight into Javascript Prototype Inheritance

An oft-used type of inheritance in JavaScript is Prototype Inheritance, which, as the name suggests, works through prototypes. Pointers to remember about Javascript Prototype Inheritance:

• Every JavaScript object has an internal property referred to as [[Prototype]].
• JavaScript objects are equipped with a link to a 'prototype' object.

Applying Javascript Prototype Inheritance in Coding Ventures

But how does Prototype Inheritance come in handy during actual coding? Here's a telling example:

function Vehicle(speed, mileage) {
  this.speed = speed;
  this.mileage = mileage;
}

function Car(color) {
  this.color = color;
}

Car.prototype = new Vehicle(100, 10);

In the example of code above, the Car function is using the prototype property to inherit the properties of the Vehicle object.

Practical Application of Javascript Inheritance

The application of Javascript Inheritance in practical development processes is something every developer should familiarise themselves with. This involves implementing Functional Inheritance or Object-Oriented Inheritance, based on the requirements of your task.

Functional Javascript Inheritance Example

Taking things forward, let's initially consider a simple example scenario to demonstrate functional inheritance in JavaScript. Consider that you have a generic object, say, a 'Vehicle'.

function Vehicle(type, speed) {
  this.type = type;
  this.speed = speed;
}

Vehicle.prototype.describe = function() {
  return "This " + this.type + " moves at " + this.speed + " mph.";
}

A 'Car' and 'Plane' can be considered as specific variants of a 'Vehicle'. Both 'Car' and 'Plane' share certain properties with 'Vehicle' but have their own distinct properties too. Through Functional Inheritance, you can establish this relationship.

function Car(type, speed, color) {
  Vehicle.call(this, type, speed);
  this.color = color;
}

function Plane(type, speed, altitude) {
  Vehicle.call(this, type, speed);
  this.altitude = altitude;
}  

As evident from the above code snippet, the Car and Plane objects inherit the properties of the Vehicle object using the `Vehicle.call(this, type, speed);` feature of Functional Inheritance.

Tips for Using Function Inheritance in Javascript Effectively

Utilising Javascript Inheritance in a practical context requires proficiency and a keen understanding of some specifications.

• Always use the 'new' keyword to create a new object using a constructor function.
• Be careful when setting the prototype of an object - Javascript might use the constructor prototype by default.
• Rely on 'instanceof' if you need to check whether an object is an instance of a particular constructor.
• Remember that methods allocated via the 'prototype' keyword are shared amongst all instances of an object, which makes your code more memory efficient.

Discovering Javascript Object-Oriented Inheritance

Another form of Inheritance worth exploring is Object-Oriented Inheritance. In Javascript, this style of inheritance is facilitated mainly through the class syntax. Consider an example with a 'Parent' class and a 'Child' class, with the 'Child' class inheriting from the 'Parent' class.

class Parent {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
}
class Child extends Parent {
  constructor(name, age, grade) {
    super(name, age);
    this.grade = grade;
  }
}

In this scenario, the 'Child' class extends the 'Parent' class, thereby including the all properties of the 'Parent' in addition to its own. This is Object-Oriented Inheritance in action.

The Importance of Javascript Object-Oriented Inheritance in Web Development

While Object-Oriented Inheritance with Javascript might not seem that different from Functional Inheritance, it carries its own weight when it comes to certain aspects.

• It provides clearer, more intuitive syntax and is easier to understand for developers coming from a class-based language background.
• It can help organise your code into more coherent and maintainable structures, particularly when your codebase becomes complex.
• It allows subclassing or extending classes, which opens up avenues for more flexible and robust code.

To conclude, mastering Javascript Inheritance - be it Functional or Object-Oriented - can give you an edge as a web developer. Understanding these concepts can not only help you write more efficient and maintainable code but also help you understand the inner workings of Javascript at a deeper level.

Navigating Through Javascript Multiple Inheritance

The concept of Javascript Multiple Inheritance, although not supported directly, can be a tricky terrain to manoeuvre. Let's demystify this for you.

Handling Javascript Multiple Inheritance: A Guide for Students

Javascript Multiple Inheritance forms a part of the vast arrays of inheritance techniques. However, notably absent in the realm of JavaScript, is the built-in support for multiple inheritance using just the prototype property. Objects in JavaScript have a feature called the prototype chain which enables them to inherit methods and properties from other objects specified as their prototype. But, the question arises: Can a single object have multiple prototypes? Can it have a prototype-chain to multiple objects? The answer is no, not directly.

function SuperHero(name, power){
 this.name = name;
 this.power = power;
}

function Flying(powerOfFlight){
 SuperHero.call(this, 'Flying Hero', 'Fly');
 this.powerOfFlight = powerOfFlight;
}

Flying.prototype = new SuperHero();

In this example, you might consider the Flying SuperHero a product of multiple inheritance. But in reality, this is just Function Borrowing or Copying. The SuperHero properties are borrowed or copied to the Flying function, but this is not multiple inheritance because Flying does not have a direct link or prototype chain to the SuperHero's prototype object. However, multiple inheritance in JavaScript can be achieved through indirect ways, like using mixin or the copying methods.

The Controversies Surrounding Javascript Multiple Inheritance

Despite its compelling benefits, multiple inheritance often bears the brunt of criticism. The chief among them concerns the Diamond Problem. The absence of built-in support for multiple inheritance in JavaScript is often looked at as a design choice meant to avoid such problems. Remember that although techniques like mixins and copying can simulate multiple inheritance, they are not entirely free from issues. Potential risks involving property collision could still surface.

Strategies for Implementing Multiple Inheritance in Javascript

There are several techniques that you can adopt to work around the initial hurdle of lack of built-in multiple inheritance support in JavaScript. Here is a comprehensive layout of two widely-used strategies: mixins and copying.

Practical Roadmap: Multiple Inheritance with Mixins

Here, we discuss mixins, poring over what they are and their application to achieve multiple inheritance. By making use of mixins, you essentially 'mix' an object with other objects to form a single object that has all the required functionalities. A straightforward example of using mixins in JavaScript would be:

let flyMixin = function(obj) {
  obj.fly = function() {
    console.log("Flying!");
  }
};

let bird = {
  name: "Sparrow",
  speed: "10 m/s"
}

flyMixin(bird);
bird.fly();

A key advantage of mixins lies in the modular nature in which the functions are written, leading to organised and manageable code structure.

Harnessing Multiple Inheritance with Copying

Multiple inheritance in JavaScript can also be implemented by copying properties from one object to another. This typically involves two steps:

• Create an instance of the parent class.
• Copy the properties of the instance to the child class.

The code snippet below gives you an illustrative example:

function Dog(name, breed) {
  this.name = name;
  this.breed = breed;
}

function Cat(name, color) {
  this.name = name;
  this.color = color;
}

function CatDog(name, breed, color) {
  Dog.call(this, name, breed);
  Cat.call(this, name, color);
}

Here, the CatDog function is created by copying properties from both the Dog and Cat function using the `call()` method. While this might sound like a dream come true, it segues into the issue of property collision if the parent classes have a property of the same name. As such, leveraging this strategy demands careful design considerations.

Real-world cases: How Multiple inheritance in Javascript drives Complex Projects

Despite the tricky paths you have to navigate, Multiple Inheritance has an immense bearing on real-life coding ventures. From enhancing your code reusability to enriching objects with multiple behaviours, it can be a potent tool to streamline sophisticated projects. A case in point is game development, particularly in defining game characters with multiple abilities. Through multiple inheritance, you can conveniently equip a single character class with visual, audio and physics properties, inherited from their corresponding parent classes. However, you must remember that implementing multiple inheritance in your projects requires a sound understanding of JavaScript principles and astute planning to circumvent potential pitfalls.