Prototypal Inheritance is a revolutionary OOP technique that allows real-world objects to be modeled in an efficient and intuitive manner. This approach differs from the traditional class-based model of object orientation, as it involves creating new instances based on existing ones and inheriting their properties for further use. For instance, when working with JavaScript, one object can delegate its missing properties to another one present on this platform. When applied correctly, Prototypal Inheritance enhances our productivity by providing us with simpler ways of manipulating complex entities from reality!
The prototype object in JavaScript
Every object created in the prototype chain will have access to all properties and methods defined by this master object. If a new object is constructed, it looks up its own property or method first before delegating to the prototype for anything missing. By leveraging what already exists on the master template, objects can save time while still taking advantage of powerful features like inheritance and encapsulation.
// Define a master object with properties and methods
let masterObject = {
property1: 'value1',
property2: 'value2',
method1: function() {
console.log('This is method1 from the master object');
},
method2: function() {
console.log('This is method2 from the master object');
}
}
// Create a new object that inherits from the master object
let newObject = Object.create(masterObject);
// Access properties and methods on the new object
console.log(newObject.property1); // Output: "value1"
console.log(newObject.property2); // Output: "value2"
newObject.method1(); // Output: "This is method1 from the master object"
newObject.method2(); // Output: "This is method2 from the master object"
// Add new property and method to the new object
newObject.property3 = 'value3
As you can see, newObject has access to the properties and methods defined on masterObject and newObject also has its own property3 and method3, this means that if the property or method is not present in the new object, it will be looked up on the master object.
The Object.create() method is used to create the new object and set the master object as its prototype. The new object inherits all properties and methods from the master object, but can also define its own properties and methods.
How does Prototypal Inheritancerelate to inheritance in JavaScript?
Prototypal Inheritance is a type of inheritance in JavaScript where objects inherit from other objects directly instead of from a class as in traditional object-oriented programming. It is based on the prototype chain, which means objects can access properties and methods from the prototype object they are linked to. This allows objects to share properties and methods between each other.
Understanding the prototype chain
The prototype chain is the mechanism by which objects in JavaScript inherit properties and methods from their prototype object. Every object has a prototype object that it is linked to. When a property or method is accessed on an object, the JavaScript interpreter will first search the object itself, then the prototype object, then the prototype object’s prototype object, and so on up the chain until the property or method is found or the top of the chain is reached. This is how prototypal inheritance works in JavaScript.
// define a prototype object
const prototypeObject = {
name: 'prototype',
sayHello: () => console.log('Hello!')
};
// create an object, linked to the prototype object
const obj = Object.create(prototypeObject);
// access a property from the prototype object
console.log(obj.name); // 'prototype'
// access a method from the prototype object
obj.sayHello(); // logs 'Hello!'
How the JavaScript engine looks up properties and methods on objects
When a property or method is accessed on an object, the JavaScript engine will first look on the object itself. If it can’t find it, then it will look to the object’s prototype. If it can’t find it there either, then it will keep looking until it reaches the null value prototype. This chain of objects allows properties and methods to be inherited from one object to another.
Examples of how to use the prototype chain to create complex object hierarchies
The prototype chain is a powerful tool for creating complex object hierarchies. For example, when creating a game using JavaScript, one can create a base character class that contains all of the basic methods and variables the player character will need. Then any further characters in the game (such as NPCs or enemies) can inherit from this class without needing to redefine all of the methods and variables again. Similarly, one can create a base enemy class that is inherited by weaker or stronger enemies in the game. By using the prototype chain, complex object hierarchies can be created with minimal code, saving both time and memory.
Using class-based syntax for prototypal inheritance
JavaScript now allows us to use a class-based syntax for prototypal inheritance, supplying not only an easier and better organized way of writing object-oriented code but also enabling us to benefit from all the features offered by the prototype chain. This makes it possible to write object-oriented codes with greater clarity and efficiency. For example, instead of manually defining the properties and methods that a character should inherit from its base class, one can instead just extend the base class and add any new properties or methods that are needed. This provides an efficient way of writing code while still taking advantage of prototypal inheritance.
With all these powerful features, it’s no wonder why JavaScript is one of the most popular programming languages in the world! Prototypal Inheritance is an invaluable tool for creating complex and powerful software applications quickly and effectively.
Comparison of class-based syntax and the prototype-based pattern.
Here is an example of our previous prototype object written in class form.
// Class-based Syntax
class MasterObject {
constructor() {
this.property1 = 'value1';
this.property2 = 'value2';
}
method1() {
console.log('This is method1 from the master object');
}
method2() {
console.log('This is method2 from the master object');
}
}
class NewObject extends MasterObject {
constructor() {
super();
this.property3 = 'value3';
}
method3() {
console.log('This is method3 from the new object');
}
}
let newObject2 = new NewObject();
console.log(newObject2.property1); // Output: "value1"
console.log(newObject2.property3); // Output: "value3"
newObject2.method3(); // Output: "This is method3 from the new object"
This diagram represents the prototype object as a rectangle with a label “prototypeObject” that serves as the template for other objects, represented as rectangles with labels “inheritingObject1” and “inheritingObject2”. The inheriting objects are connected to the prototype object by a line with an arrowhead pointing towards the prototype object.
The inheriting objects also have a connection to Object.create method that creates the new object that inherits from the prototype object, and a class-based syntax represented as a box with a label “classObject” which is linked with two new inheriting objects inheritingObject3 and inheritingObject4 with arrowhead pointing towards the classObject.
It’s clear that with class-based syntax, your code becomes more readable and organized. Furthermore, it makes extending the master class’ functionality a breeze as well as generating an instance of said class. Above all else, this type of syntax assists in stopping unintentional overrides or collisions from occurring.
You also have the ability to use inheritance and encapsulation in an organized way, and make the code more readable and maintainable.