Moderne, a company that provides solutions to help modernize code, announced that its Lossless Semantic Tree (LST) code model now supports JavaScript and TypeScript.
LST is a format-preserving code model that captures syntax, types, symbols, dependencies, control and data flow, and whitespace.
With today’s announcement, LST can now model Java, JavaScript, TypeScript, and common Infrastructure-as-Code formats.
According to Moderne, this support is coming at a time when many organizations are needing to deal with JavaScript upgrades, like moving from Node.js 20, which is now deprecated on GitHub Actions, to Node 24.
Several util type-checking methods have been deprecated since Node.js 22, like util.isArray(), util.isBoolean(), and util.isDate(). To upgrade to Node 24, developers would need to track down every instance of these methods and replace them with the modern equivalent.
“Spread across thousands of repositories, this becomes slow, error-prone, and nearly impossible to track with confidence,” Moderne wrote in a blog post.
Moderne’s refactoring platform, OpenRewrite, can detect every deprecated method call, replace them with the proper native JavaScript equivalent, and update imports automatically.
“Because the LST understands types, it can distinguish between util.isArray() and an unrelated isArray()function, eliminating both false positives and missed cases. The result is a precise, safe migration executed across the entire codebase,” Moderne explained.
OpenRewrite’s changes can also be integrated into existing build and release pipelines to align with existing validation and governance processes. Additionally, OpenRewrite helps with vulnerability management by tracing untrusted inputs across applications and finding the locations of vulnerable libraries in the code.
“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.”