TypeScript vs JavaScript: Differences and Which to Use

Despite the word "Script" appearing in both language names, there are differences between JavaScript and TypeScript that you, as a coder, should know. Learning which one to use for your project can make your life easier and optimize your project. 

Let's look at similarities and differences between TypeScript and JavaScript, including what works best in different scenarios.

What is TypeScript?

TypeScript is a programming language built on JavaScript. It adds more structure and organization to your code, making it easier to write and maintain. TypeScript also helps catch errors before running the code (something JavaScript cannot do, as we'll discuss later). 

It provides developers with tools for collaboration, improves code readability, and allows for better code documentation. TypeScript compiles to plain JavaScript, so it can be used on any platform that supports JavaScript. It is a popular choice for large projects and teams, providing additional reliability and scalability for JavaScript development.

Differences Between TypeScript and JavaScript

If TypeScript and JavaScript are so similar, what are the differences—and why do they matter?

Static vs Dynamic Typing

Static and dynamic typing are approaches used in programming languages to handle so-called "variable types," or the different types of data that can be stored in a variable. 

JavaScript has dynamic typing, meaning you can assign different values to a variable without explicitly declaring its type. This flexibility allows for rapid prototyping but can lead to runtime errors if unexpected types are used. For example, you might start with a variable "age" storing the number 25, but later in code you might assign the string "thirty" to the same variable. JavaScript allows you to flexibly change the variable's type on the fly, which can be both convenient and potentially lead to unexpected results.

TypeScript, on the other hand, introduces static typing, which requires variables to be declared with specific types. This helps catch errors during development, improves code documentation, and provides better tooling support. However, static typing requires more upfront effort and can feel more restrictive for small projects or quick scripting tasks. Returning to the example above, you can declare the variable "age" as a number, and TypeScript will ensure it can only store numeric values. If you try to assign any other type to "age," TypeScript will show an error during development, helping you catch bugs early and write more robust code. 

Object-Oriented Programming (OOP) Support

Object-oriented programming (OOP) is a programming paradigm that organizes code around objects containing data and behavior. It promotes modularity (breaking a large problem into smaller, manageable parts that can be solved independently), reusability, and easier code maintenance. 

Both TypeScript and JavaScript support OOP, but TypeScript provides more robust support due to static typing. In TypeScript, you can define classes (which are blueprints defining how objects should be created and what they can do), interfaces (contracts defining the methods and properties an object must have), inheritance (where a new class can inherit or acquire characteristics from an existing class), and access modifiers (words controlling the visibility or accessibility of variables and methods within a class) to create robust and predictable object-oriented structures. 

OOP in TypeScript is useful for large projects where code organization and scalability are crucial. It helps create modular and maintainable codebases, promotes code reuse, and ensures better collaboration among developers working on the same project.

Type Inference

Another difference between TypeScript and JavaScript lies in their approach to type inference. Type inference refers to the language's ability to automatically determine a variable's type based on the value assigned to it. This means you don't need to explicitly declare the type every time. It improves developer productivity by reducing repetitive type annotations. 

Type inference in TypeScript speeds up development, makes code cleaner, and improves readability. It is especially useful when working on small projects or writing short code snippets where explicit type declarations may not be necessary, allowing developers to focus on writing code rather than defining types.

Due to JavaScript's dynamic typing (see above), types are determined at runtime rather than during writing, meaning it can be harder to catch errors before execution, increasing project runtime.

Scalability

In the context of coding, scalability refers to a codebase's ability to handle increasing complexity and size without becoming unmanageable. 

JavaScript is great for small projects and can handle moderate growth, but it can become harder to manage as projects grow larger and more complex. JavaScript's advantage is its ability for rapid prototyping and flexibility. However, the downside is that code can become messy and difficult to maintain without careful organization.

TypeScript has more advantages for scalable projects than JavaScript because its static typing allows developers to catch errors early, ensure code consistency, and provide better tooling support (see below) for refactoring and maintaining large codebases. It enforces stricter rules and provides type checking, making it easier to scale a project as it grows. TypeScript's additional features, such as interfaces and classes, contribute to code organization and modular development, making it a preferred choice for scalable applications.

Tooling

Tooling refers to software tools and utilities that help developers efficiently write, debug, and manage code. 

JavaScript has a variety of tools that help developers efficiently write and manage code. There are many code editors and linters (tools that help identify and highlight potential errors, style violations, and best practices), making it easier to write code and catch errors. However, JavaScript lacks a built-in tool ecosystem, so developers have to select and configure their own. This can be overwhelming for beginners but provides workflow flexibility for experienced developers.

TypeScript has more robust tooling support compared to JavaScript. TypeScript's tooling includes powerful code editors like Visual Studio Code, which offer features such as intelligent code completion, error highlighting, and refactoring support (having tools that help change and improve code without altering its behavior). Additionally, TypeScript has a dedicated compiler that checks for errors and generates JavaScript code.

Performance

TypeScript and JavaScript have similar performance characteristics because TypeScript ultimately compiles to JavaScript. Performance depends on various factors, including code efficiency, algorithms used, and the runtime environment. 

Both languages can be optimized for performance by following best practices such as minimizing unnecessary computations, optimizing loops, and reducing memory usage. Performance testing is crucial to identify bottlenecks and optimize code. Tools like Chrome DevTools and profiling libraries can help analyze and improve performance for both TypeScript and JavaScript. 

It's important to note that while TypeScript offers static typing, which can catch some errors and improve code optimization, it does not provide a significant performance advantage over JavaScript.

Use Cases for TypeScript

TypeScript, as an enhanced version of JavaScript, has several practical applications. Here are some of the most common use cases for TypeScript.

• Large-Scale Web Development. TypeScript is useful for building large and complex web applications. Its static typing helps catch errors early in development, making code more reliable and maintainable as the project grows.
• Collaborative Codebases. TypeScript's static typing allows multiple developers to work on the same codebase more efficiently. Clear type annotations and interfaces make it easier to understand and collaborate on different parts of the code.
• Frameworks and Libraries. TypeScript is widely used in frameworks and libraries like Angular, React, and Vue.js. It enhances their capabilities by providing type checking, autocompletion, and improved tooling support, enabling developers to build robust and scalable applications that TypeScript is known for.
• API Development. TypeScript is useful for building application programming interfaces (APIs)—sets of rules and protocols that allow different software applications to communicate and interact with each other and with backend services. It provides type safety and better code organization on the server side, resulting in more maintainable and error-free APIs.
• Cross-Platform Development. TypeScript can be used to develop cross-platform mobile applications using frameworks like Ionic and NativeScript. It allows code sharing across different platforms and ensures consistent behavior and type safety across iOS, Android, and web applications.

Use Cases for JavaScript

JavaScript is a versatile programming language with several practical use cases. Here are a few examples.

• Website Interactivity. JavaScript is one of the most popular programming languages for website development because it can create dynamic, interactive content for static web pages. 
• Browser Extensions. JavaScript is the primary language for creating browser extensions, which add extra functionality to web browsers. These extensions can customize browser behavior, block ads, enhance productivity, and integrate with other web services.
• Game Development. JavaScript, along with HTML5 canvas and WebGL, enables the development of browser-based games like Hero Wars and Forge of Empires. It is robust enough to handle complex online gaming requirements such as game logic, user input, graphics, and animation.
• Server-Side Development. When used as a front-end development language, JavaScript also allows for building scalable and efficient server-side applications, APIs, and even full-stack web development.