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Robert Johns | 09 Feb, 2024
Fact checked by Jim Markus

What is JavaScript? Introduction To JavaScript For Beginners

What is JavaScript? If you want the TL-DR, JavaScript is a versatile programming language essential for adding interactivity to websites.

But it’s so much more than that!

That’s why I’ve written this article about JavaScript, covering its key features, applications, ecosystem, how easy it is to learn, strengths and weaknesses, and the future of JavaScript.

I’ll even show you how to write your first JavaScript program.

So, join me as we dive deep to answer the question: what is JavaScript?

What Is JavaScript?

JavaScript is a cornerstone of the modern web, shaping the interactive experiences we've all come to expect from websites and web applications. 

Created in the mid-1990s by Brendan Eich while at Netscape, JavaScript has transcended its initial purpose as a simple scripting tool for enhancing HTML web pages. 

Originally named Mocha, then LiveScript, it was quickly rebranded to JavaScript, reflecting Netscape's collaboration with Sun Microsystems to incorporate the Java language into its Navigator browser. 

This naming, however, has often led to confusion, as JavaScript's relationship with Java is more akin to marketing strategy than technical lineage. Just check out the syntax, and you’d be hard-pressed to see them as related!

From its inception, JavaScript was designed to be approachable for web designers and developers, offering a means to add interactivity, animate page elements, validate forms, and more directly within the browser environment. 

Its adoption was further solidified when the ECMAScript standard was established, providing a specification for JavaScript's core features and ensuring consistency across different web browsers.

The evolution of JavaScript is a testament to its adaptability and the vibrant community that has grown around it. 

With the arrival of AJAX (Asynchronous JavaScript and XML) in the early days of modern web design, JavaScript enabled more dynamic web pages, leading to the web applications we use today. 

I still remember paying with AJAX during my early days of web development and being blown away!

Then there’s the introduction of jQuery, a fast and concise JavaScript library that also simplified how we interacted with HTML documents, handled events, and performed animations, marking a significant leap in web development practices.

And, of course, there’s the rise of Node.js, which extended JavaScript's reach to server-side programming. This was huge, as it meant developers could build entire web applications with a unified language for both client and server-side scripts. 

This server-side revolution, coupled with the development of JavaScript frameworks like React, Angular, and Vue.js, has not only cemented JavaScript as a language for adding interactive features to web pages but as a language capable of powering complex web applications.

Today, JavaScript's influence extends beyond the web, finding applications in mobile app development, desktop applications, and even Internet of Things (IoT) devices. 

Its continued evolution, driven by an active community and the ongoing development of the ECMAScript standards, ensures JavaScript remains at the forefront of technology, adapting to the ever-changing demands of the digital world.

What Are JavaScript’s Key Features?

As a versatile and dynamic programming language, JS boasts a range of key features that have contributed to its widespread use and popularity in web development and beyond.

1. Interpreted Language

JavaScript is typically an interpreted language, meaning that JavaScript code is executed line by line by the JavaScript engine within the web browser or Node.js environment. 

This allows for a high degree of flexibility and dynamism in web development, as scripts can be written and run on the fly without requiring a compilation step. 

This interpreted nature contributes to the ease of testing and debugging JavaScript code, as developers can quickly write, modify, and execute code snippets in real time, observing immediate results.

2. Dynamic Typing

JavaScript is a loosely typed or dynamically typed language, meaning variables don't need to be declared with a specific type, and their types can change at runtime. 

This flexibility allows you to write less code and achieve functionality without the strict type constraints found in statically typed languages. 

That said, it also requires a careful approach to avoid type-related errors.

3. First-Class Functions

In JavaScript, functions are treated as first-class citizens, which means they can be passed as arguments, assigned to variables, and even returned from other functions.

This allows for high-order functions and functional programming techniques, which are central to many of JavaScript's powerful programming patterns, including callbacks and closures.

4. Object Orientation with Prototypes

JavaScript uses prototypes for inheritance, so each object in JavaScript can have a prototype object, which acts as a template from which the object inherits methods and properties. 

This prototype-based model allows for more flexible and dynamic object construction and inheritance patterns, fitting well with JavaScript's dynamic nature.

5. Asynchronous Programming

JavaScript has strong support for asynchronous programming, primarily through callbacks, promises, and async/await syntax. 

This is particularly useful in web development for handling tasks like fetching data from a server, where operations might take an unpredictable amount of time. 

Asynchronous programming helps in executing such tasks without blocking the main thread, ensuring the smooth performance of web applications.

6. Event-Driven Programming

JavaScript is inherently designed to respond to user interactions within the web browser, making it event-driven. 

Developers can easily set up event listeners to react to user actions like clicks, keyboard input, or mouse movements, allowing for the creation of interactive and responsive web interfaces.

7. Client-Side Execution

Originally designed to run in browsers, JavaScript executes on the client side, enabling immediate interaction without the need to communicate with the server for every action. 

This execution capability is crucial for creating fast and fluid user experiences on the web.

8. Interoperability

JavaScript is highly interoperable with other web technologies, seamlessly integrating with HTML and CSS to create dynamic content. 

It can manipulate the Document Object Model (DOM) to dynamically change the content, structure, and style of web pages.

9. Rich Standard Library and Ecosystem

JavaScript comes with a rich standard library that offers built-in objects and functions to perform common tasks, from mathematical operations to manipulating dates and strings. 

Perhaps more importantly, the JavaScript ecosystem is vast! 

This means you get access to many JS libraries and frameworks, like React, Vue.js, and Angular, which extend JavaScript’s capabilities and streamline web development.

The Applications of JavaScript

JavaScript's versatility and widespread adoption have led to its use in a myriad of applications across the web and beyond. 

Initially conceived to add interactivity to web pages, JavaScript has grown to encompass a broad range of core uses and applications, significantly shaping the digital landscape.

1. Dynamic Web Pages

At its core, JavaScript enhances web pages by adding interactivity and dynamic content. 

It allows web developers to create responsive forms, animate page elements, and respond to user events like clicks, mouse movements, and keyboard inputs, making web pages more engaging and user-friendly.

2. Single-Page Applications (SPAs)

JavaScript is pivotal in developing SPAs, where most of the application's content is loaded on a single web page. 

Through AJAX calls and modern frameworks like Angular, React, and Vue.js, SPAs can update content dynamically without reloading the page, offering a seamless and app-like experience within the browser.

3. Front-End Web Development

JavaScript, along with HTML and CSS, forms the triad of cornerstone technologies for front-end web development. 

It's used to create interactive and dynamic user interfaces, control web page behavior, and manipulate the Document Object Model (DOM) to dynamically change the content and appearance of web pages.

4. Back-End Development with Node.js

Node.js, a JavaScript runtime built on Chrome's V8 JavaScript engine, extended JavaScript's reach to the server side, enabling developers to use JavaScript for backend development. 

This has led to the creation of full-stack JavaScript applications, where both the client and server layers are written in JavaScript, streamlining development workflows and reducing context switching for developers.

Note that whenever you see the terms MERN or MEAN stacks, that the ‘N’ in these is Node.js!

5. Real-Time Applications

JavaScript is widely used in developing real-time applications like chat applications, live content updates, and interactive gaming. 

Technologies like WebSockets and libraries such as Socket.io, combined with Node.js, enable efficient real-time communication between clients and servers.

6. Web Servers and Server Applications

With Node.js, JavaScript can be used to build web servers and server applications, handling HTTP requests, accessing databases, and serving dynamic content. 

This has popularized JavaScript in building RESTful APIs and microservices architectures.

7. Mobile Application Development

Thanks to frameworks like React Native or Ionic, you can also take advantage of JavaScript to build and code mobile apps for iOS and Android. 

These frameworks are handy because they enable code reuse across platforms, significantly reducing development time and effort while maintaining a native-like user experience.

8. Cross-Platform Desktop Applications

Electron and NW.js are frameworks that leverage JavaScript to create cross-platform desktop applications for Windows, Mac, and Linux. 

You’ve probably even used some of the more popular apps that use Electron, including VSCode, Slack, and even Discord. 

These are ideal examples of how JavaScript is useful beyond standard web apps.

9. Internet of Things (IoT)

JavaScript is also making inroads into the IoT space, with low-code platforms like Node-RED offering an easy way to wire together things like hardware devices, APIs, and online services. 

The event-driven and non-blocking nature of Node.js makes JavaScript suitable for IoT applications that require handling a large number of concurrent connections and real-time data.

10. Game Development

While not as dominant as C# in Unity or C++ in Unreal Engine, JavaScript is used in web-based game development, particularly with HTML5 Canvas and WebGL for 2D and 3D graphics. 

Frameworks like Phaser have popularized JavaScript in the indie game development community for creating browser-based games.

The JavaScript Ecosystem

The JavaScript ecosystem is truly vast and dynamic, encompassing a wide array of frameworks, development tools, and community resources that cater to various aspects of web and software development. 

This rich ecosystem is one of the main reasons for JavaScript's enduring popularity and its ability to adapt to the evolving landscape of technology.

Frameworks and Libraries

JavaScript's ecosystem is perhaps most renowned for its diverse range of frameworks and libraries, each designed to solve different problems or simplify specific tasks in web development. 

Some of the most notable frameworks and libraries include:

  • React: Developed by Facebook, React is a library for building user interfaces, particularly known for its virtual DOM feature that optimizes rendering and facilitates the development of interactive UIs.
  • Angular: A comprehensive framework backed by Google, Angular offers a robust platform for developing scalable single-page applications, complete with a wide array of built-in functionalities, from two-way data binding to dependency injection.
  • Vue.js: Vue.js is a progressive framework that is highly adaptable and accessible, making it a popular choice among developers for its ease of integration and gentle learning curve.
  • Node.js: Although not a framework, Node.js deserves mention as an essential part of the JavaScript ecosystem, extending JavaScript's reach to server-side development, enabling full-stack JavaScript applications.

These tools, among others like Express.js for server-side operations and Next.js for server-side rendering in React applications, showcase the versatility and breadth of JavaScript's ecosystem, catering to a wide range of development needs.

Integrated Development Environments (IDEs) and Editors

The development experience in JavaScript is further enhanced by a variety of IDEs and code editors designed to streamline coding, debugging, and testing. Popular choices include:

  • Visual Studio Code (VS Code): Developed by Microsoft, VS Code is a lightweight but powerful source code editor that comes with built-in support for JavaScript, TypeScript, and Node.js, along with a vast marketplace of extensions for additional languages, tools, and debuggers.
  • WebStorm: A specialized IDE for JavaScript development from JetBrains, WebStorm offers advanced coding assistance for JavaScript, HTML, and CSS, along with powerful navigation and refactoring tools.
  • Sublime Text: Known for speed and efficiency, Sublime is a versatile text editor favored for its clean interface and extensive customization options. Its "Goto Anything" feature, powerful editing capabilities, and an array of plugins make it ideal.

Community and Support

A significant part of JavaScript's success lies in its vibrant and active community. 

Numerous online forums, social media groups, and websites are dedicated to JavaScript learning and problem-solving, including:

  • Hackr.io: Here at Hackr, we not only find the best online JavaScript courses and resources, but we also provide step-by-step tutorials and educational content for beginners and pros alike.
  • Stack Overflow: A vital resource for developers seeking quick solutions to coding challenges, offering a vast repository of JavaScript questions and answers.
  • GitHub: Many open-source JavaScript projects are hosted on GitHub, providing a wealth of code examples, libraries, and frameworks for developers to use and contribute to.
  • MDN Web Docs: Maintained by Mozilla (think FireFox), MDN Web Docs is a detailed and free resource offering docs, guides, and tutorials on JavaScript and web development.

In addition, conferences like JSConf, meetups, and hackathons around the world offer opportunities for learning, collaboration, and networking within the JavaScript community.

How Easy Is It To Learn JavaScript?

How easy is it to learn JavaScript, really?

Well, I’d say it depends on your own background in programming, your familiarity with web technologies, and your preferred learning style. 

That said, JavaScript is widely considered as one of the easiest languages for beginners, thanks to its straightforward syntax, the immediate feedback loop provided by web browsers, and abundant learning resources.

Let’s take a deeper dive.

Approachable Syntax

JavaScript's syntax is influenced by several well-known programming languages, including Java, C, and Python, making it relatively easy to grasp for individuals with some programming background. 

Even for complete beginners, JavaScript's syntax is designed to be intuitive and readable, with a flexible structure that forgives small errors, making the initial learning curve less steep.

Immediate Application

One of the most encouraging aspects of learning JavaScript for beginners is the ability to see immediate results. 

Since JavaScript is executed in the web browser, learners can write simple scripts and immediately run them in the browser to see the effects, providing instant gratification and a tangible sense of progress.

Abundant Resources

The JavaScript community is vast and supportive, offering a wealth of learning materials tailored to all skill levels. 

From interactive tutorials and online JavaScript courses to comprehensive documentation and community forums, you have access to a diverse set of resources, including:

  • Online Platforms: Websites like freeCodeCamp, Codecademy, and Hackr.io offer interactive JavaScript courses that guide beginners through the basics with hands-on exercises.
  • Video Tutorials: Platforms like YouTube have countless tutorials and lecture series on JavaScript, covering everything from basic concepts to advanced topics.
  • Documentation and Books: The MDN Web Docs provide a thorough and authoritative reference for JavaScript, while books like "Eloquent JavaScript" offer in-depth insights and practice exercises.

Community Support

As I just mentioned, the JavaScript community is known for being welcoming and helpful to beginners. 

Whether you’re using our resources at hackr or looking in online forums like Stack Overflow and Reddit's r/learnjavascript, there are lots of active spaces where newcomers can ask questions, seek advice, and share their learning experiences.

Advantages & Strengths of JavaScript

As a pivotal language in web development and beyond, JavaScript offers many advantages that contribute to its widespread adoption and, frankly, massive popularity. 

Ubiquity and Universality

JavaScript is natively understood by web browsers, making it universally applicable across the web. 

This ubiquity means JavaScript code can run on virtually any device with a web browser, from desktop computers to smartphones and tablets, providing a wide reach for JavaScript aps.

Versatility

JavaScript's versatility is one of its greatest strengths, as it's used for front-end development with libraries like React and Angular, for server-side development with Node.js, and even in mobile app development with frameworks like React Native. 

This flexibility allows you to use JavaScript across the entire development stack, enabling full-stack development with a single language.

Rich Ecosystem

The JavaScript ecosystem is truly vast and very dynamic, with a wealth of libraries, frameworks, and tools that streamline development processes and enhance functionality. 

This is one of my favorite things about JavaScript, as it means I can build complex applications more efficiently by leveraging pre-built solutions for common development tasks.

Strong Community Support

JavaScript is known for having one of the biggest developer communities. 

This vibrant community contributes to a wealth of resources, including open-source projects, forums, tutorials, and documentation, making it easier for developers to learn, troubleshoot, and stay updated with the latest trends and best practices.

Event-Driven and Asynchronous Programming

JavaScript's event-driven nature, coupled with powerful features like callbacks, promises, and async/await, makes it particularly good for developing highly interactive and responsive applications. 

In fact, this asynchronous programming capability is essential for tasks that require non-blocking operations, such as network requests or file I/O to ensure smooth performance and UX.

Rapid Development and Prototyping

JavaScript's interpreted nature and dynamic typing are ideal for rapid development and prototyping, allowing you to quickly test ideas and iterate on your JavaScript projects

The immediate feedback loop provided by web browsers is also fantastic at further accelerating development, making JS an excellent choice for startups and projects with tight deadlines.

Enhanced User Experience

JavaScript plays a crucial role in creating dynamic, interactive web pages that respond to user inputs without the need for page reloads. 

This interactivity enhances the user experience (UX), making web applications more engaging and intuitive.

Integration With Other Web Technologies

JavaScript integrates seamlessly with other core web technologies like HTML and CSS, enabling you to manipulate web page content and styles programmatically. 

This close integration is essential for creating rich, interactive web applications that leverage the full capabilities of modern web browsers.

Continuous Evolution

One of the keys to JavaScript’s lasting success is the willingness to evolve continually, as shown by the regular updates that are released for the ECMAScript standard.

This ongoing development ensures that JavaScript remains relevant and capable of addressing the changing needs of modern web development with a host of new features and improvements. 

Challenges & Limitations of JavaScript

While JavaScript is undeniably versatile and powerful, it's not without its challenges and limitations. 

I think it’s essential for developers to understand these drawbacks to navigate the complexities of JavaScript development effectively and to apply best practices for optimal results.

Browser Compatibility

A longstanding challenge with JavaScript relates to inconsistencies across different web browsers. 

Despite significant improvements and standardization efforts, variations in how browsers interpret JavaScript can lead to discrepancies in functionality and user experience. 

This means you may need to employ polyfills or transpilation tools like Babel to ensure cross-browser compatibility.

Performance Constraints

While JavaScript engines have become incredibly fast, JavaScript's dynamically typed nature and high-level abstraction can introduce performance bottlenecks, especially in computationally intensive tasks. 

This is particularly noticeable in comparison to lower-level, compiled languages optimized for speed and efficiency.

A great example is when you compare JavaScript with a newer language like Web Assembly, which allows you to code in languages like C/C++ and Rust for execution at near-native speeds.

Security Concerns

As primarily client-side language, JavaScript poses inherent security risks, such as cross-site scripting (XSS) attacks, where malicious scripts are injected into web pages to steal user data or manipulate the DOM. 

This means developers must follow best security practices, like input validation and content sanitization, to mitigate these vulnerabilities.

Dynamic Typing Double-Edged Sword

JavaScript's dynamic typing offers flexibility but can also lead to runtime errors and bugs that are hard to track down, as type coercion can result in unexpected behavior. 

This has even led to many large-scale enterprise apps adopting static type checkers like TypeScript, which adds a layer of type safety on top of JavaScript.

Callback Hell and Complexity

This term always makes me chuckle, but in all seriousness, asynchronous programming in JavaScript, particularly with the traditional callback pattern, can lead to "callback hell," where nested callbacks create complex, hard-to-maintain code structures. 

While modern features like promises and async/await have addressed this to a large extent, managing asynchronous code remains a challenge for developers, especially beginners.

Memory Management

JavaScript's garbage-collected environment simplifies memory management but can also lead to inefficiencies, such as memory leaks in long-running applications. 

This means developers need to be mindful of memory usage and the lifecycle of objects to ensure optimal performance.

Tooling Complexity

The modern JavaScript development workflow often involves a complex toolchain, including transpilers, bundlers, and task runners. 

Setting up and maintaining these tools can be daunting for newcomers and can add overhead to projects, especially for beginners.

What Does The Future Hold For JavaScript?

Now you know that JavaScript is immensely popular and has been for quite some time, what does the future hold?

Let’s tackle this question now.

Continued Evolution of ECMAScript

The ECMAScript standard, which underpins JavaScript, is regularly updated with new features and improvements. 

Future versions of ECMAScript are expected to introduce more syntactic sugar, enhance performance, and improve language clarity and developer experience. 

Features like decorators, private class fields, and a pipeline operator are among the proposals that could further enrich the language.

WebAssembly Integration

WebAssembly (Wasm) is emerging as a complementary technology to JavaScript, allowing code written in languages like C, C++, and Rust to run on the web at near-native speed. 

I love this idea because, rather than constantly leaning on JavaScript, Wasm allows you to open up new possibilities for performance-critical applications and complex web-based games, potentially broadening the scope of what can be achieved within the browser environment.

I’d even go so far as to say that it might become one of the languages you need to know in the future if you want to stand out as a JavaScript developer.

I, for one, will be curious to see if it features in the 2024 edition of the Stack Overflow developer survey!

Expansion of JavaScript Beyond the Browser

JavaScript's reach continues to extend beyond web browsers into other domains, such as server-side development with Node.js, mobile app development with frameworks like React Native, and even desktop applications with Electron. 

I think the future may even see JavaScript's influence expanding into further areas like IoT, virtual and augmented reality, and machine learning, further solidifying its role as a versatile and ubiquitous language.

Enhanced Tooling and Frameworks

The JavaScript ecosystem is known for its vibrant array of frameworks and tools. I think we can expect continued innovation in this space, with existing frameworks evolving and new ones emerging to address the changing needs of web and application development. 

The focus will likely be on improving performance, enhancing developer ergonomics, and simplifying state management and data handling.

Focus on Performance and Optimization

As web applications become increasingly complex, I think there will be a greater emphasis on optimizing JavaScript performance. 

This includes advancements in JavaScript engines like V8 (Chrome), SpiderMonkey (Firefox), and JavaScriptCore (Safari), as well as the development of tools and best practices for code optimization, lazy loading, and efficient resource management.

Emphasis on Security

With the growing prevalence of web-based applications in everyday life, security will remain a major concern. 

I think we can anticipate more robust security features and best practices within the JavaScript ecosystem to mitigate vulnerabilities and protect against emerging threats.

Community and Collaboration

The JavaScript community's spirit of collaboration and open-source contribution will continue to drive the language's evolution. 

I think initiatives like TC39 (the committee responsible for ECMAScript standards) and open-source contributions will play crucial roles in shaping the future of JavaScript, guided by real-world use cases and developer feedback.

Getting Started With JavaScript

Okay, you know everything there is to know about JavaScript, and you’re just itching to start coding, right?

Well, if you’re a total beginner, why not start with the classic "Hello, World!" 

I love starting beginners with this because it’s super simple, a rite of passage for new programmers, and also a great way to get acquainted with the basics of a JavaScript program.

Step 1: Set Up Your Environment

All you need to start writing JavaScript is a web browser (like Chrome, Firefox, or Edge) and a simple text editor like Notepad or TextEdit, or even an advanced editing tool like Visual Studio Code or Sublime Text.

Step 2: Create Your HTML File

JavaScript often interacts with HTML, as this is the standard markup language for creating web pages. 

For this exercise, you'll embed JavaScript code within an HTML file. 

Start by opening your text editor and creating a new file. Save it with a .html extension, for example, hello_world.html.

Step 3: Write Your HTML Structure

Type the following basic HTML structure into your file:

<!DOCTYPE html>
<html>
<head>
  <title>My First JavaScript</title>
</head>
<body>

</body>
</html>

This sets up a basic webpage. The <title> tag gives the browser's tab a title, and the <body> tag is where the content of your page will go.

Step 4: Adding JavaScript

Now, it's time to introduce JavaScript. Within the <body> tags, add a <script> tag. This is where your JavaScript code will live. 

For the "Hello, World!" program, you'll use the alert() function, which displays a message in a pop-up window in the browser. 

Here's how:

<script>
alert('Hello, World!');
</script>

Your complete file should now look like this:

<!DOCTYPE html>
<html>
<head>
  <title>My First JavaScript</title>
</head>
<body>

  <script>
      alert('Hello, World!');
  </script>

</body>
</html>

Step 5: Open Your File in a Web Browser

Save your HTML file and then open it with your web browser. You can usually do this by double-clicking the file, right-clicking it, and selecting your browser from the "Open with" menu or by dragging the file into an open browser window.

When the HTML file loads, your JavaScript code executes, and you should see a pop-up alert box displaying the message "Hello, World!"

You've just written your first piece of JavaScript code. While this is a simple start, it's your entry into the world of programming with JavaScript. 

From here, the possibilities are vast. You can learn to manipulate web page elements, respond to user actions, fetch data from servers, and much more. 

Be sure to check out more JavaScipt projects if you want to get hands-on to learn more. I particularly like the JavaScript Drum Kit!

When you’re ready, consider taking your JavaScipt career to the next level by trying to earn a JavaScript certification, as this will really make your resume pop!

Wrapping Up

So there you have it; the next time someone asks, what is JavaScript? You’ll be ready to tell them it’s the powerhouse behind the interactive and dynamic facets of the web.

You’ll also be ready to let them know that JavaScript stands as the backbone of modern web development, seamlessly integrating with HTML and CSS and bolstered by an expansive ecosystem of frameworks and libraries like React, Angular, and Node.js. 

We’ve also covered JavaScript's key features, applications, strengths and weaknesses, and the future of JavaScript. I’ve even shown you how to create your first "Hello, World!" program with JavaScript.

Whether you're a budding programmer or a seasoned developer, one thing is for sure: mastering JavaScript can open many doors in your career, so have fun and happy coding!

Want to sharpen up your JavaScript and web development skills? Check out:

Udemy's Complete JavaScript Course From Zero to Expert

 

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By Robert Johns

Technical Editor for Hackr.io | 15+ Years in Python, Java, SQL, C++, C#, JavaScript, Ruby, PHP, .NET, MATLAB, HTML & CSS, and more... 10+ Years in Networking, Cloud, APIs, Linux | 5+ Years in Data Science | 2x PhDs in Structural & Blast Engineering

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