TypeScript vs JavaScript
TypeScript is a superset of JavaScript that adds static typing, compiled away before the code runs. Every valid JavaScript file is already valid TypeScript - the question is whether the added type-checking is worth the extra build step and learning curve.
For small scripts or quick prototypes, plain JavaScript's lack of ceremony is genuinely faster to write.
Side by side
| TypeScript | JavaScript | |
|---|---|---|
| Type checking | None - types are only known at runtime | Static, checked at compile time |
| Build step required | No - runs directly | Yes - compiles down to JavaScript |
| Error detection | Many errors only surface at runtime | Many errors caught before running the code |
| Learning curve | Lower - nothing extra to learn | Higher - requires learning the type system |
| Editor tooling | Good autocomplete via inference | Significantly better autocomplete and refactoring support |
| Best fit | Small scripts, quick prototypes | Larger codebases, teams, long-lived projects |
The verdict
For small scripts or quick prototypes, plain JavaScript's lack of ceremony is genuinely faster to write. For anything larger - a team codebase, a long-lived application, a public library - TypeScript's compile-time error catching and editor tooling tend to pay for the extra setup many times over as the project grows.
Frequently asked questions
01Do I have to rewrite my JavaScript to use TypeScript?
No - TypeScript can be adopted incrementally, since valid JavaScript is already valid TypeScript; types can be added file by file over time.
02Does TypeScript slow down runtime performance?
No - TypeScript's types are entirely compile-time; they're stripped away before the code runs, so there's no runtime performance cost.
03Is TypeScript required for React or Node.js?
No - both work fine with plain JavaScript, but TypeScript has become the de facto standard in many professional codebases for the safety it adds.