JavaScript to TypeScript Converter

Convert JavaScript code to TypeScript instantly with automatic type inference and syntax transformation.

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About This Tool

This online JavaScript to TypeScript converter allows you to transform JavaScript code into TypeScript quickly and accurately. Simply upload your .js files or paste JavaScript code directly, and the tool will automatically convert it to TypeScript with proper type annotations, interface definitions, and modern TypeScript syntax. The converter handles ES6+ features, async/await, classes, and common patterns to produce clean, type-safe TypeScript code ready for your projects.

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How to Use

Upload a JavaScript file (.js) using the file upload area or paste your JavaScript code into the text area.
Configure conversion options like strict mode or interface generation if needed.
Click the 'Convert to TypeScript' button to process your code.
View the converted TypeScript code in the results section.
Download the converted TypeScript file or copy the code to your clipboard.

Frequently Asked Questions

Find Quick Answers

How accurate is the JavaScript to TypeScript conversion?

The converter uses Babel's parser and TypeScript compiler APIs to accurately transform JavaScript syntax to TypeScript, including type inference for variables, functions, and parameters. While it handles most common patterns well, complex dynamic JavaScript may require manual type refinement.

Does the converter support ES6+ features like async/await and classes?

Yes, the tool fully supports modern JavaScript features including ES6 classes, async/await, arrow functions, destructuring, and modules, converting them to their TypeScript equivalents with proper type annotations.

Can I convert multiple JavaScript files at once?

Currently, the tool processes one file or code snippet at a time. For multiple files, you can convert them individually or combine them into a single file before conversion.

What happens to JavaScript types during conversion?

The converter infers TypeScript types from your JavaScript code using static analysis. It adds type annotations to function parameters, return types, variables, and generates interfaces for object structures when possible.

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