One of the most frequent questions that people asked me is that: “Should I start with TypeScript or with JavaScript?” I used to provide a well-balanced answer weighing the pros and cons of each. Nowadays, I tend to ask one single question in response: “What are you building?”
The short answer is: if you are building something simple or a prototype, use JavaScript; if you are building something you plan to develop further, spend more time on or work together with other people, use TypeScript. However, there’s a little more to it than that.
The Fundamental Relationship: TypeScript is JavaScript Plus Guardrails
Let’s begin with clearing up a lot of confusion about this topic first of all. TypeScript is a superset of JavaScript. Imagine it as JavaScript, but with some restrictions imposed, like guardrails along the highway rather than an open road. Every piece of code written in JavaScript is also TypeScript, which means if you have knowledge of JavaScript, then you also know about TypeScript basics.
TypeScript was developed by Microsoft in 2012 due to the size of JavaScript codebases and problems related to finding bugs associated with simple type errors. Dynamic typing was the core of the issue.
Dynamic Typing vs. Static Typing: At the Core of the Issue
This is one of the key differences that you need to grasp. In JavaScript, all variables have dynamic typing, which means that you can change the type of data that a certain variable can hold at runtime. This may cause confusion when coding.
javascript
let myVariable = 42; // It's a number
myVariable = "Hello"; // Now it's a string, and JavaScript doesn't care
function addNumbers(x, y) {
return x + y;
}
let result = addNumbers(5, "10"); // JavaScript turns "10" into a number and gives you 15. No error, just... what you might not expectLoose typing and automatic type conversions in JavaScript could be the cause of some hard-to-detect bugs. The more JavaScript code you look at, the easier it becomes to see this for yourself.
The statically typed language TypeScript was designed to make sure that you specify the type of data that a particular variable should contain (for example, string, number, or boolean). This checking will be done by the TypeScript compiler (tsc).
typescript
let myVariable: number = 42; // Explicitly a number
myVariable = "Hello"; // 🚫 TypeScript Compiler Error: Type 'string' is not assignable to type 'number'.
function addNumbers(x: number, y: number): number {
return x + y;
}
let result = addNumbers(5, "10"); // 🚫 Compiler Error: Argument of type 'string' is not assignable to parameter of type 'number'.TypeScript immediately flags the type error and throws an exception at compile time. This way, you will be able to spot an entire class of bugs right when you are writing your code.
Impact of TypeScript on Your Work Process
JavaScript: Fast and Flexible
Advantages of JavaScript:
JavaScript’s greatest asset is its simplicity. JavaScript allows you to start coding and run your code immediately, without any need for compiling. It is an ideal tool for prototyping, scripting, and any project where the requirements change from day to day. And JavaScript is undoubtedly the language of the web.
Disadvantages of JavaScript:
Without a safety net, this is a significant disadvantage as the project becomes bigger. All it takes is one typo in the name of a property, or giving a function that expects a number, a string, and a run-time error will be thrown. These kinds of errors are hard to catch because they happen when a certain path is hit by the end user in production.
TypeScript: Structure and Safety
Advantages of TypeScript:
One main advantage of using TypeScript is that it helps find errors at compile time and not runtime. This makes for a better, safer, and cleaner code. The type system works as a built-in documentation system, where just by looking at the signature of the function, you get to know about the input and output it provides, for example, function fetchUser(id: number): Promise.
TypeScript significantly boosts developer experience.
- Superior Tooling: TypeScript provides better IntelliSense (autocompletion), inline documentation, and safe refactorings due to its types, which VS Code, for example, takes advantage of. Just this feature is enough to dramatically increase developer efficiency.
- Safer Refactoring: You can safely rename or modify functions because the TypeScript compiler warns you about broken links when you do that. You’ll be able to develop your code base aggressively and safely.
- Faster Onboarding: Having the definition of types allows new developers to understand what is going on in the code. It serves as a “smart friend.”
Performance Consideration: TypeScript translates into JavaScript code. This implies that the code that finally executes within your web browser or Node.js is clean and optimized JavaScript code. There will be no overhead performance difference between a well-structured JavaScript application and a TypeScript application at the run-time level.
Indirect SEO Advantage of TypeScript
The following aspect may go unnoticed by most people: TypeScript does not have any effect on SEO whatsoever. The reason being, the Googlebot will never see any code written in TypeScript since all the code is compiled into JavaScript.
Nevertheless, there is an indirect SEO advantage brought about by TypeScript. Because of bug prevention, the page will be able to operate effectively and will not show any kind of faulty metadata (e.g., undefined title). It will not even produce incorrect JSON-LD schema mark up for rich snippets.
When to Use JavaScript?
The use of JavaScript is appropriate when performance and ease of development outweigh the benefits of compilation.
- Prototype and MVP Development: The code may need to be rewritten in just a few weeks. Configuration of tsconfig.json is an additional step that does not provide an equivalent value.
- Scripting and Automation: Development of build scripts, CI automation, helper tools, etc., are perfect candidates for JavaScript due to its natural asynchronous I/O capabilities and absence of compilation.
- Small Project: A landing page or an internal application may work better using the simplicity of JavaScript.
- Basics Learning: Due to its nonexistent configuration steps, JavaScript is the default language used by beginners. The developer can simply open the browser console and start playing with it.
Starting with JavaScript: The Pragmatic Path
This is going to sound harsh, but it doesn’t mean anything bad. It is perfectly pragmatic to start with JavaScript. Not in the sense that it is easier than other languages; rather, because it reduces friction in forming mental models. Simply type commands into the browser console or .js file and execute the code.
There is no configuration and no compilation. That kind of immediate feedback is helpful when you are learning basic principles of coding, including variables, functions, flow control, arrays, objects, and async patterns. Adding types to the list is counterproductive at this stage.
How to Actually Start
- Browser console, day one… That’s it.
- A simple HTML file with a
<script>tag. See how the DOM works. - Node.js for command-line scripts. File I/O, HTTP requests, the whole backend story.
- Build something. A to-do list. A weather app. A tiny API server. The project teaches you, not the tutorial.
When to Use TypeScript?
The more significant your codebase and the number of people involved, the more useful TypeScript is going to be to you. TypeScript is the best choice when:
- Creating Big, Complicated Projects: With a large number of files, modules, and people working on them, a type system will help greatly.
- Building Long-Term Products: Any software product that is going to be developed and expanded for several years (SaaS, enterprise applications, etc.) will be much less buggy with TypeScript.
- Working with Large Teams: TypeScript serves as an agreement between developers and significantly decreases coordination costs.
- Developing Critical Software: Finance, healthcare, and other data-driven industries cannot afford mistakes. TypeScript will help detect them beforehand.
- Using Modern Frameworks: If you are working with Angular, Next.js, NestJS, or SvelteKit, then you are already in a TypeScript-friendly environment.
Starting with TypeScript
If you’re convinced and are ready to try out TypeScript, think small-scale. One of the biggest advantages of TypeScript is that it can be adopted gradually.
- Installing TypeScript: Install the compiler globally: npm install -g typescript
- Renaming a File: Rename .js files into .ts files. Since all valid JavaScript is valid TypeScript, it will compile just fine! And there’s nothing stopping you from using an extremely permissive tsconfig.json file.
- Adding Type Annotations: Begin with adding some type annotations, such as “string” or “number,” to some of the function parameters.
- Installing Type Definitions: With regard to npm packages, you’ll usually have to install type definitions separately for the package: npm install @types/package-name. In case there are no type definitions, you can always fall back on any.
It’s common practice to gradually move towards using TypeScript while keeping legacy code in JavaScript. The “gentle approach” allows one to experience all of the benefits of TypeScript without a big rewrite.
Conclusion: Pick the Tool, Not the Team
To make it clear: There is no competition between JavaScript and TypeScript, and they are not battling each other in the holy wars of programming languages. While one of them provides amazing performance and simplicity, another brings order and security into the development process, which makes collaboration and maintenance possible.
My personal opinion: Once I was rather avoiding using TypeScript because of the additional effort. However, nowadays I find myself using TypeScript by default for any of the projects I am working on. The initial overhead is absolutely worth having a “smart friend” who is going to catch my mistakes even before I commit to a repository. Just give it a try. You will probably notice the difference in a few minutes.
