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)

RPC Resurgence: From Client-Server Applications to Next.js and Meta Frameworks - JSJ 607

RPC Resurgence: From Client-Server Applications to Next.js and Meta Frameworks - JSJ 607

AJ, Chuck, and Dan join this week's panelist episode. They dive into the resurgence of RPC (Remote Procedure Call) in JavaScript frameworks and the potential benefits and drawbacks of combining front-...

14 Marras 20231h 39min

Mastering ORM with TypeScript - JSJ 606

Mastering ORM with TypeScript - JSJ 606

Lars-Erik Roald is a software developer at Systor. He shares his insights and experiences in creating ORM and the evolution of the technology. They dive into the world of ORMs, TypeScript, and a varie...

7 Marras 202357min

TypeScript, ESLint, and TypeScript ESLint with Josh Goldberg - JSJ 605

TypeScript, ESLint, and TypeScript ESLint with Josh Goldberg - JSJ 605

Josh Goldberg is a full-time open-source developer. He begins by sharing his developer experience and what he is currently working on. He joins the show to talk about "TypeScript, ESLint, and TypeScri...

31 Loka 20231h 17min

What has Changed with htmx 2.0 with Carson Gross - JSJ 604

What has Changed with htmx 2.0 with Carson Gross - JSJ 604

Carson Gross returns to the show to talk about htmx 2.0. He begins by explaining what's new with htmx, its interesting features, the services it offers to its users, misconceptions about it, and many ...

24 Loka 20231h 21min

Harnessing Module Federation and Micro Front-Ends in JavaScript Development - JSJ 603

Harnessing Module Federation and Micro Front-Ends in JavaScript Development - JSJ 603

Vitor Alencar is a technical lead, speaker, and creator. He joins the show to talk about module federation, its benefits, and how it works. Additionally, they dive into an insightful discussion on mic...

17 Loka 202357min

View Transitions API with Noam Rosenthal - JSJ 602

View Transitions API with Noam Rosenthal - JSJ 602

Noam Rosenthal is a Web platform engineer. They dive into the importance of standards in API behavior for browsers. Noam shares insights on the need for consistency in implementing standards across di...

10 Loka 20231h 26min

Accessibility in Component Libraries with Maya Shavin - JSJ 601

Accessibility in Component Libraries with Maya Shavin - JSJ 601

Maya Shavin is a Senior Software Engineer at Microsoft. She joins the show to talk about accessibility in component libraries for developers. They talk about choosing component libraries when creating...

3 Loka 20231h 16min

Unraveling the CSS Revolution, Podcast Growth Tactics, and More - JSJ 600

Unraveling the CSS Revolution, Podcast Growth Tactics, and More - JSJ 600

Robbie Wagner and Charles Carpenter from "Whiskey Web and Whatnot" join this week's episode, featuring some exciting updates in the world of web development. CSS enthusiasts will be thrilled to hear a...

26 Syys 20231h 21min

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