TypeScript vs. JavaScript: A Guide

TypeScript and JavaScript are two similar programming languages for web development. Although each takes a different typing approach, they remain popular among developers. JavaScript ranks third in the August 2024 PYPL Popularity of Programming Language Index, and TypeScript also makes the top ten at number eight [1]. 

Developers often turn to these languages, but how do you decide which best suits your application? It helps to understand the distinct features of each as well as each language’s pros and cons. Explore these important considerations before comparing and contrasting TypeScript versus JavaScript, and learn about applications in which you can use these programming languages. 

What is JavaScript?

JavaScript is an object-oriented programming language with a dynamic typing approach that makes it useful in website and game development, mobile apps, and building web servers. However, its primary use case is browser scripting. Its object-oriented nature allows you to reuse your code and efficiently maintain programs since an error to one object generally won’t hinder other functions.

JavaScript is a client-side programming language, meaning a browser processes the code rather than a server. Client-side and server-side distinctions are comparable to differences between front-end and back-end development. They mainly refer to whether the application code runs on an individual device, which is regarded as the “client,” or on a server.

You can insert JavaScript into an HTML document as executable code. The browser will read and interpret the code and react to events, such as a page loading or a user clicking, and the browser will execute the program. The executed code may appear as a click-to-show dropdown menu, additional content on the page, or elements on the page changing colors. Any dynamic or interactive features you see on a web page are likely the work of JavaScript.

While desktop and mobile applications can typically only run on the specific operating systems you write them for, a JavaScript application can run on any device and every browser. This means JavaScript code will reliably function on Windows, Mac OSX, Linux, iPhone, and Android devices. 

Java vs. JavaScript

Java inspires JavaScript, but they differ in several ways. While JavaScript is an interpreted language, Java is a compiled language. Java needs to run through a compiler before a machine can execute it. In other words, the Java source code requires translation into machine code, bytecode, or another programming language to be compatible with different devices. Meanwhile, the browser reads and interprets JavaScript, executing it without a compiler, making JavaScript faster to run.

Another key difference between Java and JavaScript is that JavaScript does not require you to declare your variable data types as you do in Java. In programming, variables are the entities that act or are acted upon, and the variable data type determines the kinds of operations that the variable can perform or have performed on it. All variables in Java must have a data type; however, with JavaScript, the interpreter can infer the data type of a given variable without the programmer having to define it., saving time during scripting. Still, you may encounter many bugs in your code since the data types of your variables may change each time you run your code.  

Advantages of using JavaScript

Explore some of the valuable benefits of coding in JavaScript, making it popular among programmers. These include:

• Speed: Since the script compiles and runs client-side, you can execute faster than a program that needs to communicate with a server. 

• Versatility: If you run JavaScript through the Node.js platform, it can work at both ends of web development (the client- and server-side). It also runs in every web browser and on any device without a plugin, making writing cross-platform apps easier. 

• Popularity: JavaScript has a variety of add-ons that can help extend what you do with the language. Node.js is a popular platform that often powers games and natural language processing tools like chatbots.

• Ubiquity: Because it is so common, you can easily find resources online and supportive communities to answer your questions as you learn.

• Client-side actions: JavaScript can validate user data before sending it to the server because it runs through a browser or browser engine.

Disadvantages of using JavaScript

Despite its benefits, users can also experience downsides when using JavaScript. Consider the following disadvantages of JavaScript when choosing your programming language:

• Security concerns: This dynamic code executes on the user’s device without variable type checks until it runs. So, errors can make it through. Likewise, since JavaScript runs pop-up ads, internet browsers may also disable your code.

• Inconsistencies: You may encounter inconsistencies in how different web browsers interpret this client-side script. 

What is TypeScript?

Microsoft developed this open-source programming language. It is a superset of JavaScript that adds supplementary syntax to JavaScript code to support better integration with your editor. This means you can add a few lines of TypeScript syntax to your JavaScript code, highlighting errors you can correct before runtime. In this way, all JavaScript programs can be TypeScript programs by adding a few lines of code. Unlike JavaScript, however, TypeScript needs a compiler to execute its script, and TypeScript requires you to declare variable types. It can lead to slower programming with TypeScript initially but fewer errors with your code in the long run.

First introduced to the public on GitHub in 2012, TypeScript runs on any browser or app that JavaScript runs on, and it can run advanced JavaScript features on older browsers that generally could not support them. TypeScript applies data types to your JavaScript code, declaring the kinds of operations that can be performed on a given variable so that you can more easily catch and prevent mistakes in your code. TypeScript can also apply type assertions, type guards, and type aliases to refine your JavaScript code further.

TypeScript leverages the benefits of JavaScript but is more suited to complex applications because it can audit the behavior of your code when it applies types to your code variables. TypeScript renders JavaScript, which is an untyped language, into a typed language, enabling feature enhancements that endear it to companies such as Asana and Canva.

Advantages of using TypeScript

From robust feature support to scalability, TypeScript offers various benefits. Some of the pros associated with TypeScript include the following:

• Error identification: TypeScript highlights errors in the code at compilation time. You may even avoid them with the help of the IntelliSense tooling support that works as you code.

• Feature support: TypeScript is a strongly typed and static programming language that supports optional parameters and modules. Its design-by-contract programming supports robust documentation.

• Scalability: Because TypeScript has extra type annotations, it can better process and validate contextual information.

• Integrated development environment (IDE) support: You can use TypeScript in Visual Studio and other tools to provide a single user interface for different functionalities.

Disadvantages of using TypeScript

Like JavaScript, this language also has several potential cons. Consider the following potential drawbacks of using TypeScript. 

• Execution time: TypeScript needs a compiling step before it executes, so the code can take longer to run.

• Learning curve: TypeScript is more complicated to script. Learning and using JavaScript could prove more effortless if you don’t need its added functionality.

What do JavaScript and TypeScript share in common?

All TypeScript essentially is JavaScript because TypeScript is a superset of JavaScript. Therefore, they are both object-oriented languages used to develop dynamic content and interactivity for websites and to build games, calculators, and other kinds of programs. At its core, TypeScript is just a programming language that helps developers write better JavaScript code.

Typescript vs. JavaScript

While JavaScript can run directly in a web browser, TypeScript needs a compiler to turn the code into JavaScript before running it on a browser. When you work in TypeScript, you can identify errors during compilation rather than at runtime. Ultimately, you spend less time debugging your JavaScript code after running it.

Additional features of TypeScript that differentiate it and make it a welcomed addition to JavaScript include the increased simplicity in maintaining TypeScript code and organizing components, contributing to the language's scalability. 

Common applications of JavaScript and TypeScript and notable users

Explore some of the use cases of JavaScript and TypeScript. Also, discover some of the best-known companies that use these programming languages.

JavaScript applications

You can use JavaScript to create interactive websites and applications. It could include developing:

• Websites

• Games 

• Mobile apps

• Web servers

• IoT devices 

Facebook, Twitter, WordPress, and Pinterest use JavaScript to build their websites. Google Maps is also a prominent user of JavaScript, as the code effectively underpins interactive map visualizations. 

TypeScript applications

TypeScript simplifies the development of large-scale JavaScript applications by offering the ability to declare and express types, annotate properties, variables, parameters, and return values with types. Popular companies using TypeScript include Medium, Slack, DoorDash, and Typeform. 

Beyond TypeScript vs. JavaScript: Build programming skills on Coursera

TypeScript and JavaScript are two popular programming languages [1]. TypeScript expands on JavaScript’s web page interactivity capabilities through features such as early error detection and easy integration with IDEs such as Microsoft Visual Studio.

Learning TypeScript and JavaScript can equip you to pursue a career in programming or simply help you develop and maintain your website. Start by learning JavaScript. You can do so with the JavaScript for Beginners Specialization offered by the University of California Davis on Coursera.