{"id":16216,"date":"2024-04-12T15:26:48","date_gmt":"2024-04-12T13:26:48","guid":{"rendered":"https:\/\/pagepro.co\/blog\/?p=16216"},"modified":"2026-09-14T10:42:06","modified_gmt":"2026-09-14T08:42:06","slug":"typescript-vs-javascript","status":"publish","type":"post","link":"https:\/\/pagepro.co\/blog\/typescript-vs-javascript\/","title":{"rendered":"TypeScript vs JavaScript"},"content":{"rendered":"\n

Today we will cover a wide, and hot topic: TypeScript vs JavaScript. <\/p>\n\n\n\n

Should they really be compared? This question always arises when I consider writing technology comparison. But the answer is a clear yes! Even though TypeScript is a superset of JavaScript, meaning they share a lot in common, comparing them is valuable. We’ll explore the key differences to help you choose the right language for your project.<\/p>\n\n\n\n

But before we go any further, please note:
Since TypeScript is designed to be a superset of JavaScript, and any valid JavaScript code is also valid TypeScript code. <\/strong>This design principle allows JavaScript code to be used within TypeScript files without modification, leveraging TypeScript’s benefits, such as static typing and advanced object-oriented features, while maintaining full compatibility with existing JavaScript codebases. The TypeScript compiler transpiles TypeScript code, including any embedded JavaScript, into plain JavaScript that can run in any JavaScript engine or browser. This ensures that TypeScript enhances JavaScript development without sacrificing the ubiquity and flexibility of JavaScript.<\/p>\n\n\n\n

So, we will start simply: <\/p>\n\n\n\n

What is JavaScript? <\/h2>\n\n\n\n
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JavaScript (JS) is a ubiquitous scripting language in the web development world. <\/strong>Alongside HTML and CSS, it forms the core triad for building dynamic and interactive web pages. JavaScript empowers developers to create features like real-time updates, interactive maps, and even animated graphics. Originally focused on client-side scripting, it has grown into a versatile language with Node.js enabling server-side development as well. <\/strong>Its ease of use and prevalence across web development stacks solidify its position as a fundamental tool for web developers, even with newer languages like TypeScript arising to offer supersets with features like static typing.<\/p>\n\n\n\n

What is TypeScript? <\/h2>\n\n\n\n
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TypeScript is a superset of JavaScript, designed to add static typing to the language, <\/strong>which helps catch errors early in the development process and enhances code readability and maintainability. By introducing types, interfaces, and enums, among other features, TypeScript allows developers to write more robust and error-resistant code,<\/strong> which is particularly beneficial for large-scale applications. It compiles down to plain JavaScript, ensuring compatibility with any browser, host, or operating system, and can be adopted incrementally, making it a flexible choice for projects already using JavaScript. Despite the additional layer of complexity it introduces, TypeScript’s tooling support and integration with modern development environments have made it increasingly popular among developers seeking to leverage the dynamic nature of JavaScript with the benefits of a statically-typed language.<\/p>\n\n\n\n

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I’m a big fan of TypeScript! It really cuts down on the bugs, which is a lifesaver when we’re pushing new features. And refactoring is so much smoother\u2014it’s like the code almost updates itself! <\/p>\nRafa\u0142 Dabrowski, Senior React Developer at Pagepro<\/cite><\/blockquote>\n\n\n\n

Core differences between JavaScript vs TypeScript<\/h2>\n\n\n\n

I know that’s exactly why you’re here. But to be honest, the differences here are the additional features and tools that TypeScript brings to the table, enhancing and extending the functionality of JavaScript. So the real question is: How does TypeScript improve developers’ efficiency? <\/p>\n\n\n\n

The Key Difference – Typing System<\/span><\/h3>\n\n\n\n

The primary difference between Typescript and Javascript lies in their typing systems. And it’s the one that made most developers move from plain JavaScript to TypeScript. TypeScript introduces static typing, where type checking occurs at compile-time, allowing developers to catch and correct errors before runtime. Of course, it greatly enhances error detection but also significantly improves developer tooling support, providing features such as better code completion, navigation, and refactoring capabilities. <\/strong>TypeScript’s static typing is designed to catch errors during development, promoting early detection of potential issues. <\/p>\n\n\n\n

Static typing offers significant benefits for developer productivity:<\/p>\n\n\n\n

Early Error Detection<\/h4>\n\n\n\n

TypeScript performs type checking at compile time. This means errors related to mismatched data types or incorrect function arguments are caught early in the development process, saving developers time debugging runtime errors.<\/p>\n\n\n\n

Code example – TypeScript <\/strong><\/p>\n\n\n\n

let username: string = \"John Doe\";\nlet age: number = 30;\n<\/code><\/pre>\n\n\n\n
Code example – JavaScript <\/strong><\/p>\n\n\n\n
let username = \"John Doe\"; \/\/ Type is inferred at runtime\nlet age = 30; \/\/ Type is inferred at runtime<\/code><\/pre>\n\n\n\n
TypeScript gives you the option to specify what type of data (e.g., text, number) each variable should hold.<\/strong> This is known as “type annotation.” In this example, the username is explicitly marked to hold text (string), and the age is marked to hold a number. It helps catch errors early. For instance, if someone accidentally tries to assign a number to a username, TypeScript would flag it as an error before the code is even run. <\/p>\n\n\n\n
JavaScript does not allow you to explicitly state what type of data a variable should hold. It’s inferred when the code runs. As a result, errors related to unexpected data types might only be discovered when the code is running, potentially leading to bugs that are harder to trace.<\/p>\n\n\n\n
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I like to think that TS is the shortcut for The Sentry<\/em>, because it guards the code against errors. <\/p>\nArkadiusz Kruszewski, Developer at Pagepro <\/cite><\/blockquote>\n\n\n\n
Improved Code Completion and Navigation: <\/h4>\n\n\n\n
IDEs and code editors that support TypeScript can leverage type annotations to provide more intelligent code completion suggestions and navigation features. This allows developers to write code faster and with fewer errors.<\/p>\n\n\n\n
Better Refactoring Support: <\/h4>\n\n\n\n
Because TypeScript understands the types involved in your code, it can provide more robust refactoring capabilities. Developers can safely rename variables, functions, and classes with greater confidence that unintended side effects won’t be introduced.<\/p>\n\n\n\n
Need help in choosing the right tech stack? <\/p>
talk to expert<\/a><\/div><\/div><\/div>\n\n\n\n
More advanced Object-Oriented Features in TypeScript<\/span><\/h3>\n\n\n\n
Both JavaScript and TypeScript support class-based syntax, but TypeScript extends this feature with more advanced object-oriented capabilities. These additions provide a stricter and more structured approach to object-oriented programming, making the code easier to manage and more predictable, particularly in large-scale projects.<\/p>\n\n\n\n
Interfaces and Type Checking: <\/h4>\n\n\n\n
TypeScript introduces interfaces as a way to define contracts within your code and with external code as well. Interfaces in TypeScript are a powerful way to define the shape of objects, ensuring that they meet a specific contract, which is great for ensuring consistency and predictability in large codebases.<\/p>\n\n\n\n
Example: <\/strong>TypeScript’s Interfaces let you define a structure for objects. Here’s an example:<\/p>\n\n\n\n
Code in TypeScript:<\/strong><\/p>\n\n\n\n
interface User {\n\u00a0 name: string;\n\u00a0 age: number;\n}\n\nconst user: User = { name: \"John Doe\", age: 30 };<\/code><\/pre>\n\n\n\n
Code in Javascript:<\/strong><\/p>\n\n\n\n
const user = { name: \"John Doe\", age: 30 }; \/\/ No explicit structure<\/code><\/pre>\n\n\n\n
Interfaces let you define a structure for objects. <\/strong>Here, the User interface specifies that any user object should have a name (text) and an age (number). This ensures that any user object adheres to this structure, making the code more predictable and easier to debug. In JavaScript, the structure of objects is flexible, which offers freedom but can lead to inconsistencies,<\/strong> especially in larger projects.<\/p>\n\n\n\n
Richer Access Modifiers: <\/h4>\n\n\n\n
TypeScript supports access modifiers such as public<\/code>, private<\/code>, and protected<\/code>, which help manage object properties and method visibility within classes. This is a significant enhancement over JavaScript, which only supports this level of encapsulation using closures or Symbol keys as of ES6.<\/p>\n\n\n\n
Abstract Classes and Methods<\/h4>\n\n\n\n
TypeScript allows the use of abstract classes and methods, which specify a base class that cannot be instantiated on its own but can be extended. This feature helps create a clear and enforced structure of code inheritance, which is particularly useful in complex applications where maintaining a certain hierarchy of components is necessary.<\/p>\n\n\n\n
Read-Only Properties<\/h4>\n\n\n\n
TypeScript provides readonly<\/code> properties that must be initialized at their declaration or in the constructor of the class, ensuring that they can\u2019t be changed later. This feature is useful for defining properties that should not be modified after creation, adding an additional layer of security and stability to applications.<\/p>\n\n\n\n
Parameter Properties<\/h4>\n\n\n\n
In TypeScript, you can also use parameter properties to quickly create and initialize a member in your class, streamlining class definitions by allowing you to declare and initialize members directly in the constructor parameters.<\/p>\n\n\n\n
Generics<\/span><\/h3>\n\n\n\n
Generics available in TypeScript provide a way to create reusable components that can work over a variety of types rather than a single one. This adds a significant level of flexibility and type safety to functions, classes, and interfaces. Generics allow for the creation of components that can interact with any type securely, reducing bugs and enhancing the developer’s ability to work with abstract and specific types dynamically.<\/p>\n\n\n\n
Code Example in TypeScript: <\/strong><\/p>\n\n\n\n
function identity<Type>(arg: Type): Type {\n  return arg;\n}\nlet output = identity<string>(\"myString\");\n<\/code><\/pre>\n\n\n\n
JavaScript Code Example:<\/strong><\/p>\n\n\n\n
javascript\nCopy code\nfunction identity(arg) {\n  return arg;\n}\nlet output = identity(\"myString\"); \/\/ Type is inferred at runtime\n<\/code><\/pre>\n\n\n\n
TypeScript’s “generics” allow functions to work with any data type while still maintaining type safety. <\/strong>In this example, the identity function can return any type passed to it, but it’s explicitly used with a string here. JavaScript functions can inherently work with any type of data because the language is dynamically typed. However, there’s no way to ensure type safety upfront, which can lead to runtime errors if the wrong type of data is passed around.<\/p>\n\n\n\n
JavaScript and TypeScript – Practical Development Considerations <\/h2>\n\n\n\n
Learning Curve in JavaScript vs TypeScript<\/span><\/h3>\n\n\n\n
JavaScript is known for a little gentler learning curve, <\/strong>especially for beginners. TypeScript introduces static typing, which adds an initial learning hurdle for those unfamiliar with the concept. This might involve understanding concepts like interfaces, types, and generics. And of course, once you know JavaScript, learning TypeScript won’t be easy, but you would have to learn topics like:<\/p>\n\n\n\n