] is a property of the constructor function that creates a new object, it's defined as an object that serves as a blueprint for new objects created using that constructor. When a new object is created using a constructor, it gets an internal property
] that points to the prototype of the constructor, this is not directly accessible, but you can use
] to access it.
It's also possible to modify the prototype chain by changing the object's prototype. You can use
"myObject.__proto__ = newProto"
When a property or a method is accessed in the object, the JS engine will first check the object itself, if it doesn't find it, it will look in the object's prototype, if it doesn't find it in the prototype, it will look in the prototype's prototype, and so on.
This is how the prototype chain works, it's a linked list of objects that allow JS to look for properties and methods in a hierarchical way.
It's possible to create complex prototype chains with multiple levels, where an object prototype is an object created from another constructor that has a prototype of its own. This way you can create an inheritance hierarchy where properties and methods are inherited from different objects.
It's important to note that the prototype chain is different from the other OOP languages implementation of inheritance, and it can be confusing and cause subtle bugs if not handled carefully.
Similarities between the prototype chain and the traditional OOP
There will be difference between the syntax of the wo languages so you can read the following notes if you are not familiar with them.
- classes are defined using the
[ "class" ]keyword.
[ "this" ]keyword not needed in Java (You can still access the class attributes directly without it).
[ "constructor" ]is not needed in Java, because the default constructor of parent class will be called implicitly when a new object of Child class is created.
[ "System.out.println" ]to print the value on the console.
- In Java, the
[ "main" ]method is declared in a class separately.
- Java uses
- Class properties should be accessed using
[ "." ]in both languages.
- It is a good practice to make a class that is intended to be inherited from should have protected or public fields in order to be accessible by child classes.
- In Java The main method is declared in a class separately.
[ "console.log" ]to print the value on the console.
- The uses of
[ ";" ]is not needed as a statement delimiter (except for some cases).
- Prototype properties should be accessed using
[ "." ]in both languages.
As you can see in the example above:
Both the prototype chain is different and traditional OOP provide a way for objects to inherit properties and methods from parent objects
This means that developers can create new objects that automatically have access to properties and methods defined on a parent object, without having to explicitly assign those properties and methods to the child object. This can save a significant amount of time and effort
Both the prototype chain is different and traditional OOP allow objects to be organized into hierarchies, with parent objects at the top and child objects at the bottom
This allows for a more modular and manageable structure to the codebase, where common properties and methods can be defined in parent objects, and specialized properties and methods can be defined in child objects.
Both the prototype chain is different and traditional OOP allow objects to share common properties and methods, reducing the amount of code that needs to be written
Since both allow objects to be reused and extended, making it easier to build large and complex applications. This means that developers can create new objects that inherit properties and methods from existing objects, rather than having to recreate those properties and methods each time they're needed. This can save a significant amount of time and effort.
The differences between the prototype chain is different and traditional OOP, with code examples
The prototype chain is based on a prototype-based model of inheritance, where objects inherit properties and methods directly from other objects. In contrast, traditional OOP is based on a class-based model of inheritance, where classes define the properties and methods that objects will inherit.
] internal property that references another object, in contrast, most OOP languages use classes and the extends keyword to define inheritance.
And In prototype-based OOP, there are no classes, just objects, and it is only possible to inherit properties and methods that are directly on the object's prototype, and not to classes, it can be difficult to reason about and reason about the inheritance hierarchy.
In contrast, with class-based OOP, the inheritance hierarchy is more structured and the ability to override methods allows for a more fine-grained control over the behavior of an object and its subclasses.
In prototype-based OOP, encapsulation is not enforced in the same way as in class-based OOP. Because properties and methods are directly on the object, they can be accessed and modified directly.