JavaScript to TypeScript Converter
Convert JavaScript to TypeScript with type annotations
JavaScript Input
TypeScript Output
What is JavaScript to TypeScript Converter?
Need to migrate your JavaScript code to TypeScript? This tool converts your JavaScript code to TypeScript by adding type annotations, interfaces, and proper TypeScript syntax. Perfect for modernizing your codebase or taking advantage of TypeScript's type safety features.
According to TypeScript documentation, TypeScript adds static type checking to JavaScript, making code more maintainable and catching errors at compile time. Our converter analyzes your JavaScript code and adds appropriate type annotations, making the migration process much easier.
Everything happens in your browser – your code never leaves your computer. Convert, download, and use your TypeScript code right away. Check out the JavaScript for more details.
How to Use the JavaScript to TypeScript Converter
Follow these steps to convert JavaScript to TypeScript. Each step uses the actual buttons and panels on this page.
Paste, Upload, or Load Sample
Paste JavaScript into the left panel, or click Upload to load a file. Click Sample to see example telecomm subscriber code. Example:
const subscriber = { subscriberId: "SUB-1001", plan: "Unlimited 5G", dataUsage: 45.2, status: "active" };View TypeScript Output
The right panel shows the TypeScript version. Type annotations are added, interfaces are generated. Ready for type-safe projects.
Download or Copy
Click Download to save as .ts, or Copy to clipboard. Use Clear to start fresh. All processing runs in your browser.
When You'd Actually Use This
Code Migration
Migrate existing JavaScript projects to TypeScript. Gradually convert your codebase to take advantage of TypeScript's type safety and better tooling.
Type Safety
Add type safety to your JavaScript code. TypeScript catches errors at compile time, making your code more reliable and easier to maintain.
Better IDE Support
TypeScript provides better autocomplete, refactoring, and navigation in IDEs. Convert your JavaScript to get these benefits.
Team Collaboration
TypeScript makes code more self-documenting. Types serve as documentation, making it easier for team members to understand your code.
Common Questions
Is my JavaScript code stored?
Nope. Everything happens right in your browser. Your code never leaves your computer – we don't even see it. Check out the ECMAScript for more details.
Does the conversion preserve functionality?
Yes. The converted TypeScript code works exactly the same as your original JavaScript. We only add type annotations – no logic changes. Check out the Node.js for more details.
Are all types inferred correctly?
We do our best to infer types from your JavaScript code, but you may need to manually adjust some types for complex cases. Review the output against TypeScript documentation and refine as needed.
Does it work with ES6+ features?
Yes, we support modern JavaScript syntax including ES6+, async/await, arrow functions, classes, and more. If it's valid JavaScript, we can convert it.
Can I convert TypeScript back to JavaScript?
TypeScript compiles to JavaScript, so you can use the TypeScript compiler (tsc) to generate JavaScript. But for direct conversion, you'd need to manually remove types.
Does it work with large files?
Yep. Since everything happens in your browser, it depends on your device. Small files convert instantly. Very large files (several MB) might take a few seconds.
Other JavaScript Tools You Might Need
Conversion is just one JavaScript task. Here are other tools that work well together: