What Is JavaScript?

Indeed Editorial Team

Updated 25 January 2023

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

JavaScript is a programming language used primarily for web development. Learning the basics of JavaScript is fairly simple. However, this language is highly interactive and has many complex features and nuances when used at an advanced level. As projects become more reliant on JavaScript, employers increasingly seek out candidates with strong JavaScript skills. In this article, we explain what JavaScript is, its uses and advantages and how to begin developing JavaScript skills to advance in your career.

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What is JavaScript?

JavaScript is a programming language used to create dynamic features for a web page or website. It stores information in a series of variables and uses rules that guide how users can interact with a program. JavaScript builds upon other programming languages, updating them based on user interactions and other input. Knowing JavaScript is an important qualification for many web development positions because it is the basis of creating interactive user interfaces on the web.

How does JavaScript work with other coding languages

JavaScript uses other coding languages as the basis for a web page's structure and content and builds off that structure to create dynamic page elements. One of the reasons for JavaScript's popularity is its ability to create complex and secure web features using the simplest forms of code. JavaScript, HTML and CSS all work seamlessly together to create both simple and complex web page features.

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JavaScript and HTML

Programmers use HTML, the most basic programming language, as the outline for a page's content. JavaScript directly influences and updates the HTML based on user commands, such as the click of a mouse or entering information into a web form. JavaScript controls how the web page interacts with or changes HTML content through these commands.

JavaScript and CSS

CSS outlines the visual elements on a web page. CSS interacts with JavaScript providing guidelines for how JavaScript can influence the web page. While HTML provides the content for a web page, CSS modifies the visual display through shape, colour, size and style. JavaScript can only operate within the boundaries set by the CSS code.

When to use JavaScript

JavaScript is a full-stack programming language, meaning that it can be used for both client and server communications. You can use JavaScript any time you need a web page to do something more complicated than display static information. Programmers use the highly adaptable JavaScript language to perform an unlimited number of functions, although some functions are more common than others. Some of the tasks JavaScript can perform include:

  • Reacting to mouse movements and clicks

  • Adding, changing or removing HTML content on a page

  • Responding to typing

  • Downloading files

  • Uploading files

  • Storing data through cache

  • Interacting with site visitors

  • Sending and receiving messages

These actions can be combined to create highly interactive websites that focus on user experience. JavaScript also creates a record of server issues and user errors that programmers can use to make improvements to the code.

Advantages of JavaScript

Most web pages use JavaScript as the basis of their site functions. This is largely due to the many advantages this flexible coding language provides. Some of the biggest advantages of JavaScript for use in web development include:

  • Ease of learning: Many programmers find JavaScript easy to learn because its commands are similar to English. There are also many resources available for people looking to learn JavaScript because it is so widely used.

  • Low bandwidth needs: JavaScript is a client-side language, meaning that users provide the bandwidth needed to perform an operation. This saves bandwidth for the server that runs the page.

  • Fast processing: Changes to the code are completed almost immediately after the user performs an action.

  • Interoperability: JavaScript works well with a host of other programming languages. It can be embedded into any webpage or inside the script of another programming language. This makes JavaScript a preferred option for developing web pages.

  • Rich interfaces: JavaScript offers a rich library of interfaces to web developers for creating catchy web pages.

  • Versatility: JavaScript can be used for both front-end and back-end development, making it highly versatile.

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Disadvantages of JavaScript

JavaScript is one of the most widely used web development programming languages and offers a number of advantages, but it does have a few disadvantages as well. As a web developer, it is essential for you to understand these disadvantages so that you can use the language correctly and for the right use cases. Here are a few disadvantages of using JavaScript:

  • Lack of security on the client-side: JavaScript code can be viewed by the users and this makes it possible for cybercriminals to access and use this code for malicious purposes.

  • Lack of support for older browsers: Some of the older browsers do not support the newer functions of JavaScript, and this can be a hindrance for some applications.

  • Difficult to debug the code: The debugging facility for JavaScript is not very efficient and this makes it difficult for the developers to identify and rectify a problem in the code.

How does JavaScript work?

Web browsers have engines that translate JavaScript and other code to the images, text, animation and other features you see on your screen. The engine interprets the commands from JavaScript to dynamic actions on the page. After the HTML and CSS are loaded in a browser, JavaScript performs one function at a time in the order that the code was written on the web page. This allows each element to complete an action in a logical sequence.

Importance of learning JavaScript

Here are a few reasons that make learning JavaScript important for you:

Helps in becoming a web developer

JavaScript is the most widely used programming language for web development, along with HTML and CSS. For all practical purposes, almost all the websites and web pages built today use JavaScript in some form or the other. It is the most widely used resource for adding interactive components to web pages. So, knowing how to code using JavaScript is imperative to become a web developer.

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Helps in making an informed career choice

If you plan on becoming a web developer, it is very important to learn JavaScript because it enables you to make an informed career choice. A career in web development is not possible without learning JavaScript, and once you start learning this language, you will be in a better place to decide if web development is for you. If you are already working on HTML or CSS, you can choose to learn JavaScript as this will contribute to your career growth.

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Can be an important topic for web development interview questions

Knowing JavaScript can be helpful when you are interviewing for a web developer role. Since this programming language is very extensively used in the market, there are high chances that you will be asked questions about JavaScript when you are interviewing for the role of a web developer.

The interviewer may ask you questions about JavaScript or about concepts that are common to JavaScript, HTML and CSS. To be able to answer such questions well, you need to have a thorough understanding of the important concepts of these programming languages.

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How to learn JavaScript

Learning JavaScript adds a valuable skill to your CV and gives you a greater understanding of how websites function. The basics of JavaScript are easy to learn, allowing you to expand your skills and apply them to new situations. If you are interested in a career writing code and programming web applications, follow these steps to learn JavaScript:

1. Learn HTML and CSS

Because JavaScript interacts closely with both HTML and CSS, focus on developing your understanding of each language before attempting to learn JavaScript. HTML and CSS are easy to learn, with many free guides readily available online.

2. Take an online course

Take one of the many available online courses in JavaScript to learn the basic concepts and commands of the programming language. Online courses often allow you to practice each skill you learn on a live web page, providing hands-on experience for various difficulty levels. You can start with the various free courses available on the web, and once you start getting a grasp of the basics, you can opt for a paid course that will help you learn the advanced concepts.

3. Take up personal or freelance projects

Once you start getting familiar with the concepts of JavaScript, you may start working on a personal project or choose to take up some freelance projects related to web development. This will help you get better at the concepts and learn the language properly.

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