Stories and Strategies from Converting to TypeScript

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TypeScript is great, but migrating an existing app to it can be a pain. Codecademy took multiple existing React apps and converted them to TypeScript. We'll cover how to make those kinds of conversions successful from both cultural and technical standpoints.

This talk has been presented at React Summit Remote Edition 2021, check out the latest edition of this React Conference.

FAQ

Josh Goldberg is a front-end developer who has previously worked with Microsoft and is currently on the web platform team at Codecademy. He is also experienced in converting projects to TypeScript.

Before transitioning to TypeScript in early 2019, Codecademy's main front-end app consisted of about 2,000 files primarily using React and Redux. There was also a separate design system that was used as a proof of concept for TypeScript.

The decision to transition to TypeScript at Codecademy involved understanding the team's needs and goals, promoting the benefits of TypeScript to enhance code stability and bug reduction, and generating enthusiasm among team members for the new technology.

To facilitate knowledge sharing during the transition to TypeScript, Codecademy utilized internal presentations, pairing sessions, and identified 'area experts' and 'cheerleaders' within the team to help spread understanding and enthusiasm for TypeScript.

Codecademy started by converting a minimal number of files to TypeScript to ensure compatibility with existing infrastructure. They adopted TypeScript as a syntax and build time checker without disrupting existing JavaScript code. Over time, dedicated pull requests were used for converting specific areas to TypeScript.

Typestat is a tool developed by Josh Goldberg that automatically applies deducible TypeScript conversions across multiple files. It helped streamline the process of converting Codecademy's codebase to TypeScript by automating many of the changes.

The TypeScript conversion at Codecademy started on April 2, 2019, and took approximately 259 days, concluding on December 17, 2019.

Key lessons from Codecademy's TypeScript conversion include the importance of automating repetitive tasks, preparing a style guide for consistent coding practices, separating TypeScript conversions from runtime changes, and celebrating milestones to boost team morale.

Josh Goldberg
Josh Goldberg
20 min
14 May, 2021

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Video Summary and Transcription

This Talk discusses the process of converting to TypeScript at CodeCademy. It emphasizes the importance of encouraging adoption and knowledge sharing within the team. The Talk also highlights the seamless integration of TypeScript into the existing infrastructure and build system. The strategy for converting to TypeScript involved using dedicated pull requests and automated tools. The speaker shares tips on automating changes, setting up a styling guide, and celebrating victories. Resources for learning TypeScript are also mentioned.

1. Introduction to Converting to TypeScript

Short description:

Hello, and welcome to stories and strategies from converting to TypeScript with me, Josh Goldberg. To start off, hi, I'm from upstate New York. I'm a front end developer on the web platform team at code academy, previously Microsoft, and I'm a cat dad. Starting off, where was CodeCademy before TypeScript? Let's take a step back all the way to early 2019, a simpler time. We had a main front-end app, which at the time consisted of about 2,000 files of react and Redux, a few more files in a separate design system, which itself was converted to TypeScript as a proof of concept, and most team members had really only vaguely heard of TypeScript.

Hello, and welcome to stories and strategies from converting to TypeScript with me, Josh Goldberg. To start off, hi, I'm from upstate New York. I'm a front end developer on the web platform team at code academy, previously Microsoft, and I'm a cat dad.

My wife and I have a few cats. They're very cute. All the stuff in this presentation is available on my website under the slides link under this talk at joshuakgoldberg.com. This presentation does include several looped animated images. If those are distracting for you, I would recommend viewing them in PowerPoint, which allows you to pause them.

As for an agenda, first, we are going to talk about code academy in 2019 before we made the jump to TypeScript, how we made that decision to jump to TypeScript, some of the techniques we used for knowledge sharing on the team, technical details of what we did in order to make that jump, and then some of the learnings we got at the end throughout the process, things that you might be able to use in your conversions, I hope. Good stuff.

Starting off, where was CodeCademy before TypeScript? Let's take a step back all the way to early 2019, a simpler time. We had a main front-end app, which at the time consisted of about 2,000 files of react and Redux, a few more files in a separate design system, which itself was converted to TypeScript as a proof of concept, and most team members had really only vaguely heard of TypeScript. There wasn't a big topic or knowledge point on the team. The team itself was pretty small. It was only around 20, maybe 30 engineers at tops. Most of the people didn't really have TypeScript experience and there was, as with any engineering team, ongoing work around features and bug fixes.

So how did we do it? How did we make that switch to TypeScript? First, we made the decision that we wanted to do it in the first place, and when there's a will, there's a way, but there has to be a will. Any architectural shift should have the informed support of its constituents. I think a lot of people, especially those who are new to a team, make the mistake of immediately trying to jump to conclusions and push an agenda, send out proposals, which a lot of the time is a mistake just to do that immediately. It's a good idea to soak in the experiences of being a developer on the team, talk to people, get a feel for what the real issues are, and then use that to inform your decision making around what to push and how. Don't get me wrong. I'm not trying to devalue coming into a team with a fresh perspective and trying to get people to understand and listen to that perspective. That's great. That's commendable. Teams should absolutely be open to you coming in with fresh ideas, but those fresh ideas and perspectives are much more likely to succeed if you validate them with those around you, if you can convince people of their validity. So don't be a brat. Definitely talk to people before trying to push them to do things. If you do want to push people to do things, I highly recommend make some kind of hype train for it. If there is some switch you want to make, say a TypeScript, you want people to feel it. They should be excited in their bones.

2. Encouraging Adoption of TypeScript

Short description:

This is awesome. This is going to make my life happier and better, the code is going to work, it's going to be awesome, I want to do it. That's the feeling you want to encapsulate with perhaps some of the larger decisions you want to push on the team. Part of the way we did it was by encouraging people to think about how TypeScript helps their existing goals, always a good idea.

This is awesome. This is going to make my life happier and better, the code is going to work, it's going to be awesome, I want to do it. That's the feeling you want to encapsulate with perhaps some of the larger decisions you want to push on the team.

Part of the way we did it was by encouraging people to think about how TypeScript helps their existing goals, always a good idea. My favorite image from the evangelism phase of our TypeScript version at the very beginning was us advertising it as part of the bug acquisition funnel, as we call it, or the antifunnel. Not drawn to scale as there is no reliable scale here. No one part of this, pyrethod or peer review or whatnot can truly prevent all bugs, but put together, they can help reduce bugs and crashes on the sites. That was a big part of the team charter at the beginning of 2019, something we wanted to get better at, stability, not having bugs and annoying quirks. TypeScript is one of the core features of TypeScript, and it helps you find bugs early.

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