Introducing JavaScript


After completing this lesson, you will be able to:

  • Describe the significance of JavaScript in creating dynamic pages

Introduction to JavaScript


In the world of web development, JavaScript has earned a reputation as one of the most important and widely used programming languages. JavaScript was developed in 1995 by Brendan Eich when he worked at Netscape Communications Corporation. The original goal was to create a scripting language for the Web that would work with the Netscape Navigator browser. The language was originally called "Mocha", then briefly changed to "LiveScript", and finally named "JavaScript". Contrary to popular belief, JavaScript is not directly related to Java, despite the similar names; the naming decision was influenced by marketing strategies at the time.

The following video provides a short introduction to JavaScript.

Let's look at how core JavaScript can be extended.

  • Client-side JavaScript extends the core language by supplying objects to control a browser and its Document Object Model (DOM). For example, client-side extensions allow an application to place elements on an HTML form and respond to user events, such as mouse clicks, form input, and page navigation.
  • Server-side JavaScript extends the core language by supplying objects relevant to running JavaScript on a server. For example, server-side extensions allow an application to communicate with a database, provide continuity of information from one invocation to another of the application, or perform file manipulations on a server.

Opportunities with JavaScript

JavaScript provides a lot of opportunities.

The following video explains the opportunities provided by JavaScript.

In summary, JavaScript is a powerful and versatile programming language that has become an integral part of web development. As you begin your JavaScript learning journey, you'll gain the skills necessary to create interactive, user-friendly, and dynamic web applications that meet the evolving needs of the modern web.

Comparison of JavaScript and Java


JavaScript and Java are similar in some ways, but fundamentally different in others. The JavaScript language is similar to Java, but lacks the static typing and strong type checking of Java. JavaScript follows most of the expression syntax, naming conventions, and basic control flow structures of Java, which is why it was renamed from LiveScript to JavaScript. Unlike Java's compile-time system, which creates classes through declarations, JavaScript supports a run-time system based on a small number of data types representing numbers, Boolean values, and string values. JavaScript has a prototype-based object model instead of the more common class-based object model. Prototype-based models have dynamic inheritance; this means that inheritance can vary from object to object. JavaScript also supports functions without special declaration requirements. A function can be a property of an object implemented as a loosely typed method.

Compared to Java, JavaScript is a very free language. You don't have to declare every variable, class, and method. You don't have to worry about whether a method is public, private, or protected, or implement an interface. Variables, parameters, and function return types are not explicitly typed. Java is a class-based programming language designed for fast execution and type safety. Type safety means, for example, that you cannot convert Java integers to object references or access private memory by corrupting Java bytecode. Java's class-based model means that programs consist only of classes and their methods. Java's class inheritance and strong typing often require tightly coupled object hierarchies. These requirements make Java programming more complex than JavaScript programming.

In contrast, JavaScript descends in spirit from a line of smaller, dynamically typed languages such as HyperTalk and dBASE. These scripting languages offer programming tools to a much wider audience because of their easier syntax, specialized built-in functionality, and minimal requirements for object creation.

The following table summarizes the difference between JavaScript and Java.

Object-oriented. No distinction between types of objects. Inheritance is through the prototype mechanism, and properties and methods can be added to any object dynamically.Class-based. Objects are divided into classes and instances with all inheritance through the class hierarchy. Classes and instances cannot have properties or methods added dynamically.
Variable data types are not declared (dynamic typing, loosely typed).Variable data types must be declared (static typing, strongly typed).
Cannot automatically write to hard disk.Can automatically write to hard disk.

Role of JavaScript in Web Development


JavaScript plays a crucial role in web development because of its versatility, ease of use, and widespread use. It is one of the core technologies of the web, along with HTML and CSS.

Here are some reasons why JavaScript is essential in web development:

  • Client-side interactivity: JavaScript enables developers to add interactive elements to web pages to enhance the user experience. With JavaScript, you can create dynamic content, respond to user input, validate forms, and manipulate the DOM (Document Object Model) to change elements on a web page without reloading the page.
  • Asynchronous processing: JavaScript supports asynchronous programming that enables non-blocking operations, such as AJAX (Asynchronous JavaScript and XML). This allows developers to request data from a server and update a web page without having to fully refresh it, resulting in faster and more responsive web applications.
  • Cross-platform compatibility: JavaScript is supported by all modern web browsers, making it a universally accessible language for web development. This means JavaScript code can run on any device with a browser, ensuring a consistent user experience across platforms and devices.
  • Server-side development: With the introduction of Node.js, JavaScript has been extended beyond the browser and can now be used for server-side development. This allows developers to use the same language for both front-end and back-end development, simplifying the development process and shortening the learning curve for new developers.
  • Extensive ecosystem: JavaScript has a vast and ever-growing ecosystem of libraries, frameworks, and tools that streamline development and enable the creation of feature-rich web applications. Popular libraries and frameworks such as jQuery, Angular, React, and Vue.js have contributed to the widespread adoption of JavaScript by simplifying tasks and promoting best practices in web development.
  • Progressive Web Apps (PWAs): JavaScript is a key technology for building PWAs, which are web applications that can be installed on a user's device and run offline. PWAs combine the best features of web and native apps to deliver a more engaging user experience and higher performance.
  • Community and support: JavaScript has a large and active community of developers, which means there are numerous resources, tutorials, and support available for learning and troubleshooting. This extensive support network makes it easier for new developers to get started and for experienced developers to find solutions to their problems.

Overall, JavaScript's role in web development is crucial because of its ability to add interactivity and dynamism to web pages, its cross-platform compatibility, and its extensive ecosystem of tools and resources. Its flexibility and continuous development have made it one of the most popular programming languages for web development today.

Development Environment


Setting up the right development environment is critical for efficient and productive JavaScript development. A well-configured environment can help you write, test, and debug code more efficiently. This guide walks you through the process of setting up a development environment for JavaScript, from choosing the right code editor to installing the necessary tools and extensions.

Process to Set Up Development Environment for JavaScript

  1. Choose a code editor or integrated development environment (IDE)

    Select a code editor or IDE that suits your needs and preferences.

    Some popular options for JavaScript development include:

    • Visual Studio Code (VSCode)
    • Sublime Text
    • Atom
    • WebStorm
    • Brackets

    Each editor has its own features, so it is important to choose an editor that fits your workflow and requirements.

  2. Install editor plugins and extensions

    Enhance your development experience by installing plugins or extensions that provide JavaScript-specific features, such as syntax highlighting, code completion, linting, and formatting. Most editors have a built-in marketplace or package manager where you can browse and install extensions.

    Some popular extensions for JavaScript development include:

    • ESLint (for linting)
    • Prettier (for code formatting)
    • Live Server (for running a local development server)
    • Debugger for Chrome or Firefox (for browser debugging)
  3. Install Node.js and Node Package Manager (npm)

    Node.js is a JavaScript runtime environment that lets you run JavaScript code outside the browser. It is commonly used in server-side development and build processes. npm is the default package manager for Node.js, which you can use to manage dependencies and packages in your projects. Download and install Node.js from, which will also install npm automatically.

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