Lossless Semantic Tree code model now spans backend and frontend, giving enterprises one deterministic platform to modernize safely at scale.

Moderne, the enterprise code modernization platform from the team behind OpenRewrite, today announced full JavaScript and TypeScript support in its Lossless Semantic Tree (LST), positioning Moderne as the first deterministic modernization platform to span multiple languages and application layers. Enterprises can now bring the same precise, automated refactoring long used on the server side to their web frontends.

Modernization has long been fragmented. Teams have relied on a patchwork of codemods, AST scripts, and language-specific refactoring utilities, with no single, reliable foundation that spans stacks. Moderne’s Lossless Semantic Tree (LST) changes that: it now models Java, JavaScript, TypeScript, and common Infrastructure-as-Code formats with deep type attribution and full control- and data-flow analysis. For JavaScript and TypeScript, this is the first truly compiler-accurate, type-aware refactoring engine — moving beyond syntax-bound codemods to enable safe, large-scale upgrades and program analysis.

This change arrives at a critical moment. AI is writing more code than ever and accelerating technical debt. Forrester reports that 75% of technology leaders expect debt to rise as AI-generated code increases complexity, while GitClear’s 2025 research shows that “newly added” code has jumped from 39% to 46% of all changes since AI coding assistants became mainstream. GitHub’s Octoverse highlights the surge in AI-assisted commits. Without a semantic, cross-language foundation, organizations struggle to keep up and safely evolve sprawling, mixed-language estates.

With Moderne, engineering and security teams gain a single platform for modernization:

• Impact analysis: See where methods, types, and components are used before making changes.
• Safe, deterministic upgrades: Automated changes integrate into existing build and release pipelines with full validation and governance.
• Cross-language campaigns: Modernize backend (Java, Infrastructure as Code) and frontend (JavaScript/TypeScript) side by side.

“Enterprises don’t operate in a single language,” said Jonathan Schneider, CEO and co-founder of Moderne. “Adding JavaScript proves our vision of a universal modernization platform where backend, frontend, and infrastructure-as-code can be modernized safely and at scale.”

Many enterprises face urgent JavaScript upgrades — such as moving from Node.js 20, now deprecated on GitHub Actions, to Node 24. Until now, these migrations relied on brittle codemods and manual reviews. Moderne’s type-safe, deterministic recipes provide a scalable, reliable path to automate such changes across large, complex estates.

Security is another driver. JavaScript dependency chains are a frequent target for supply-chain exploits. Moderne’s type-attributed analysis lets security teams trace untrusted inputs across applications and locate every place a vulnerable library is used — turning modernization from a backlog problem into a proactive defense strategy.

“Context is what makes modernization safe,” Schneider said. “With the LST, we give humans and AI the same full-fidelity model of code, so changes are reliable and repeatable. Modernization can finally become a continuous capability, not a one-off project.”

JavaScript and TypeScript support is delivered under the Moderne Source Available License (MSAL) and available through the Moderne CLI and enterprise platform.

Explore how Moderne is unifying backend and frontend modernization through the world’s first type-attributed JavaScript engine, read the full blog post here.

About Moderne

Moderne automates mass-scale code modernization that’s critical to the progress and success of enterprise companies today—making a difference in minutes, not months. Moderne is based in Miami, and its investors include Acrew Capital, Intel Capital, True Ventures, Mango Capital, Allstate Strategic Ventures, Morgan Stanley, Amex Ventures, and TIAA Ventures, among other investors and advisors. To learn more, visit www.moderne.ai.

View source version on businesswire.com: https://www.businesswire.com/news/home/20251014739134/en/

Moderne adds type-attributed JavaScript and TypeScript refactoring, unifying backend and frontend modernization in one deterministic platform.