Migrating a Legacy JavaScript Codebase to TypeScript - JSJ 680
JavaScript Jabber5 Kesä 2025

Migrating a Legacy JavaScript Codebase to TypeScript - JSJ 680

In this episode, Dan and I (Steve) dove deep into what turned out to be a surprisingly complex, yet incredibly insightful topic: gradually migrating a massive legacy JavaScript project over to TypeScript. We're talking about nearly 1,000 JS files, 70,000+ lines of code, and years of developer history—all transitioning carefully to a typed, modern future.

Dan walked us through how he started by setting up the project for success before converting even one file—getting CI/CD ready, setting up tsconfig.json, sorting out test dependencies, dealing with mock leaks, and even grappling with quirks between VS Code and WebStorm debugging.

We talked tools (like TS-ESLint, concurrently, and ts-node), why strict typing actually uncovered real bugs (and made the code better!), and why it’s crucial not to touch any .js files until your TypeScript setup is rock solid.

Key Takeaways:
  • Gradual migration is 100% possible—and often better—than ripping the bandaid off.
  • TypeScript can and will catch bugs hiding in your JavaScript. Be prepared!
  • Use VS Code extensions or TS-Node to support your devs’ tooling preferences.
  • Don't underestimate the setup phase—it’s the foundation of long-term success.
  • Start small: Dan's team converted just one file at first to test the whole pipeline.
If you’re sitting on a legacy JS project and dreaming of TypeScript, this episode is your blueprint—and your warning sign.

Become a supporter of this podcast: https://www.spreaker.com/podcast/javascript-jabber--6102064/support.

Jaksot(737)

The Alphabet Soup of Performance Measurements - JSJ 622

The Alphabet Soup of Performance Measurements - JSJ 622

Dan Shappir takes the lead in explaining all of the acronyms and metrics for measuring the performance of your web applications. He leads a discussion through the ins and outs of monitoring performanc...

27 Helmi 20241h 19min

Simplifying Full-Stack Dev with the "Boring JavaScript Stack" and Sails Framework - JSJ 621

Simplifying Full-Stack Dev with the "Boring JavaScript Stack" and Sails Framework - JSJ 621

Kelvin Omereshone is the lead maintainer of Sales.js. In this episode, they uncover the complexities of the "Boring JavaScript Stack" and its implications for building full-stack web applications. The...

20 Helmi 202453min

Unpacking Core Web Vitals - JSJ 620

Unpacking Core Web Vitals - JSJ 620

Harry Roberts is a web performance consultant. They immerse themselves in the critical realm of web performance and JavaScript. The esteemed panel, including the renowned Harry Roberts, delves into th...

13 Helmi 20241h 19min

Mastering Back-End Functionalities and Development with AWS Amplify - JSJ 619

Mastering Back-End Functionalities and Development with AWS Amplify - JSJ 619

In this episode, Steve delves into a deep and insightful conversation with Erik Hanchett from Amazon AWS. They explore a wide range of topics, from discussing the possibilities and complexities of usi...

6 Helmi 20241h 10min

Exploring AI Impact on Code Generation and Quality Metrics - JSJ 618

Exploring AI Impact on Code Generation and Quality Metrics - JSJ 618

Conor Bronsdon is the host of the Dev Interrupted Podcast and currently works at LinearB. They dive into the world of generative AI tools in software development, exploring the impact, challenges, and...

30 Tammi 20241h 6min

Inside the World of React: Server Components, Unidirectional Data Flow, and Frameworks - JSJ 617

Inside the World of React: Server Components, Unidirectional Data Flow, and Frameworks - JSJ 617

Sam Selikoff is the founder of Build UI, Inc. They unpack a myriad of discussions surrounding JavaScript and its applications. They delve into topics such as RPC resurgence, React server components, a...

23 Tammi 20241h 22min

Streamlining AI Integration - JSJ 616

Streamlining AI Integration - JSJ 616

Ismail Pelaseyed is the co-founder of Superagent. They delve into the world of AI technology, open-source frameworks, and the practical applications of AI assistants. The conversation covers a range o...

16 Tammi 20241h 17min

Iterating on Open Source - JSJ 615

Iterating on Open Source - JSJ 615

Today the panel is discussing iterating on open source projects. Aimee and AJ recall a conversation they had in the past on this subject and AJ talks about some of his experience iterating with open s...

9 Tammi 202457min

Suosittua kategoriassa Liike-elämä ja talous

sijotuskasti
psykopodiaa-podcast
mimmit-sijoittaa
rss-rahapodi
rss-draivi
rss-lahtijat
oppimisen-psykologia
rss-rahamania
rss-porssipuhetta
taloudellinen-mielenrauha
rss-seuraava-potilas
rahapuhetta
rss-h-asselmoilanen
rss-paatos-podcast-suomen-kovimmat-paatoksentekijat-2
rss-paasipodi
rss-inderes
io-techin-tekniikkapodcast
pomojen-suusta
rss-viisas-raha-podi
rss-40-ajatusta-aanesta