During December 2025, JBR modernized string handling and middleware logic across the plotly.js and tanstack/router repositories. They refactored deprecated String.substr and String.substring methods to use String.slice, updating both code and tests to ensure compatibility and maintainability in JavaScript and TypeScript. JBR also addressed edge cases by fixing negative slice index handling, improving consistency across components. In tanstack/router, they enhanced middleware to return Response objects directly, supporting both synchronous and asynchronous flows and improving error management. Their work focused on future-proofing codebases, reducing regression risk, and strengthening API safety, demonstrating depth in front end and middleware development.