Syntax - Tasty Web Development Treats

992: Migrating Legacy Code Just Got Easier

58 snips
Apr 1, 2026
They discuss using AI to plan and run large codebase migrations, including mapping routes, middleware, and creating detailed test checklists. The conversation covers converting templating from Pug to JSX and building middleware to translate Express requests to web-standard Request objects. They also talk about deployment strategies, using Sentry to catch post-deploy issues, and other codebases that can benefit from AI-assisted rewrites.
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ANECDOTE

Migrating a Decade Old Express App To Hono

  • Wes Bos migrated his decade-old Express-based course platform to Hono and replaced many Pug templates with JSX/TSX.
  • He kept React for the admin/viewing apps, rewrote checkout and some routes to use Async Local Storage before mass migration.
ADVICE

Choose A Lateral Migration Path

  • Do choose a lateral move when migrating large systems to avoid scope creep and reduce risk.
  • Wes chose Hono for web-standards parity and similarity to Express so he could migrate feature-for-feature without adding new features mid-migration.
ADVICE

Incrementally Align New Code To New Standards

  • Do refactor new code toward the new platform's standards before migrating the whole codebase.
  • Wes rewrote recent routes to use Async Local Storage and extracted request data early so business logic stayed framework-agnostic.
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