Logo

Developer learning path

News
JavaScript

Prototype in JavaScript

Introduction to JavaScript
What is JavaScript? How it works? History of JavaScript
Basic Concepts in JavaScript
Variables Data Types Operators Control Flow
Functions and Data Structures
Functions Builtin functions Userdefined functions Parameters and Arguments Arrays Indexes and length Array methods
ObjectOriented JavaScript
Object and Properties Constructors Inheritance Prototype
DOM Manipulation
What is DOM? Accessing HTML elements with JavaScript Manipulating HTML elements with JavaScript Events and event handling
Asynchronous JavaScript
Callbacks Promises Async/await Asynchronous data loading AJAX
jQuery
What is jQuery? Selecting and manipulating HTML elements with jQuery jQuery events
Browser APIs
Working with Web Storage Location API Navigator API Geolocation API Canvas API
Expressions and Regular Expressions
Boolean expressions Regular expressions
Debugging and Testing JavaScript
Debugging basics Chrome Developer Tools Unit testing Testing frameworks
JavaScript Libraries and Frameworks
Introduction to libraries and frameworks React.js Angular.js Vue.js Node.js
Deploying JavaScript Applications
Deploying for the Web Hosting options
Ecmascript6 Features
Classes Arrow functions Promises Destructuring of Objects and Arrays Default parameters and Spread Operator
Security and Best Practices in JavaScript
Security basics Best practices for writing safe and maintainable JavaScript code Code optimization techniques
Conclusion
Recap of the course Next Steps.

Prototype

2

#description

In JavaScript, a prototype is an object that serves as a blueprint for other objects. Every JavaScript object has a prototype, which is inherited from the Object prototype object. A prototype-based approach is different from the class-based approach used in many other programming languages.

When you create a new object in JavaScript, it is linked to its prototype object through a special property called proto. This allows the object to access properties and methods defined on its prototype. If a property or method is not found in the object itself, JavaScript looks for it in its prototype and up the prototype chain until it reaches the Object prototype.

One of the most common use cases of prototypes in JavaScript is to add new methods or properties to an existing object. You can do this by modifying the prototype of the object's constructor function.

For example, suppose you have a Person constructor function that creates objects with a name and age property.

You can add a new method called "greet" to the Person prototype like this:

 
                    
function Person(name, age) {
  this.name = name;
  this.age = age;
}

Person.prototype.greet = function() {
  console.log("Hello, my name is " + this.name);
};

Now, all objects created with the Person constructor will have access to the "greet" method:

 
                    
var person = new Person("John", 25);
person.greet(); // outputs "Hello, my name is John"

Prototyping can be a powerful tool for creating flexible and reusable code in JavaScript. However, it requires a good understanding of how prototypes work in order to use them effectively.

March 25, 2023

If you don't quite understand a paragraph in the lecture, just click on it and you can ask questions about it.

If you don't understand the whole question, click on the buttons below to get a new version of the explanation, practical examples, or to critique the question itself.