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Migrate JavaScript to TypeScript Automatically

Upload your project and get production-ready migrated code in minutes.

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What changes between JavaScript and TypeScript?

  • File extensions renamed from .js/.jsx to .ts/.tsx across the entire codebase
  • tsconfig.json generated with strict mode and appropriate compiler options
  • Type annotations added to function parameters, return types, and variable declarations
  • PropTypes converted to TypeScript interfaces for React component props
  • Implicit any types resolved with inferred or explicit type annotations
  • CommonJS require/module.exports optionally converted to ES module import/export
  • Third-party library types installed (@types/* packages) automatically
  • JSDoc type comments converted to inline TypeScript annotations where present

How Nivo migrates JavaScript to TypeScript

01

Connect your project

Paste a GitHub URL or upload a ZIP file of your JavaScript project.

02

Nivo detects your JavaScript project

The engine scans your codebase to identify JavaScript patterns, APIs, and configuration that need updating.

03

AI applies all TypeScript migration transforms

Hybrid AST + AI engine applies deterministic transforms for configuration and dependencies, and AI-powered transforms for complex code changes. Every change gets a confidence score.

04

Download migrated codebase + review report

Get a ZIP with your fully migrated code, a complete migration report, and a checklist of items flagged for manual review.

Frequently Asked Questions

How accurate is automated JavaScript to TypeScript conversion?

Nivo uses static analysis and type inference to produce accurate type annotations. For cases where types cannot be inferred, it uses contextual analysis and marks uncertain types for your review. Typically 85-95% of annotations require no manual adjustment.

Can I migrate to TypeScript incrementally?

Yes. Nivo supports incremental migration by setting allowJs: true in tsconfig and converting files one directory at a time. You can start with strict mode disabled and tighten it gradually.

How long does a JavaScript to TypeScript migration take?

The automated conversion typically completes in 5 to 15 minutes depending on project size. Larger codebases with complex type relationships may require additional manual refinement for edge cases.

Will my existing tests still pass?

Yes. TypeScript is a superset of JavaScript, so existing runtime behavior is preserved. Your test files are also converted to .ts, and Nivo adds type annotations to test utilities and mocks.

How does Nivo handle PropTypes conversion?

Nivo maps each PropTypes validator to its TypeScript equivalent (PropTypes.string to string, PropTypes.shape to an interface, etc.), creates a typed Props interface, and removes the runtime PropTypes import.

Start your JavaScript to TypeScript migration

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