Formik: Write formik in plain js

Created on 1 Oct 2017 · 17Comments · Source: formium/formik

Hey,

Is it possible to write formik in regular js instead of typescript and keep typings in a separate folder/file/library?

It's really hard to read the codebase and contribute when you don't know typescript. There are a lot of any typings, probably half - this kinda kills the purpose of strong types.

Currently, typescript adds to formik:

cons

useful only for devs, who use TS
hard to read and contribute for regular users
requires more time to support types
pollutes codebase
almost half of typings are any

pros

helps TS devs to make few errors (not really helpful due to any typings)
makes TS devs happy to see project written in TS
?

This reminds the situation with coffescript - very hard to contribute, only for devs who know it. It'll be really great to have formik in plain js, is it possible?

Source

green-pickle

👎9 ❤3

Most helpful comment

fun to read this 2 years on :)

sw-yx on 21 May 2019

😄14

All 17 comments

I’ve thought about this a few times over the last several months. There are other benfefits to being written in JS too...

First, maintaining backwards compat in TS is more challenging when you are writing in TS. I learned this when trying to figure out how to type 0.9. Technically, the types for withFormik should have been identical to 0.8, but because of being written natively in TS I had to introduce a default any value to a generic.

Second, Formik doesn’t show up on GitHub’s rankings as JS, but under the TS language category. This has probably had a nontrivial impact on popularity.

Cognizant of the points above and the ones you’ve raised, I still don’t think moving to JavaScript is the path forward:

Typescript makes code cleaner and simpler.
My company and many companies like Uber, Slack, Lyft, Palantir, and Shopify are going all in TS React
TypeScript adds a tiny bit of friction to contributing, and I’m not sure this is a bad thing. Formik doesn’t do any crazy type stuff, but is actually a very very good introduction to TypeScript and React. If Formik can get a few devs into TypeScript, then that’s a good thing IMHO.
FYI if Reason supported an HoC pattern, Formik would be written in Reason 😎

jaredpalmer on 1 Oct 2017

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@jaredpalmer is it possible (in TS land) to have formik codebase in js and all TS typings in another file so you can import them in projects written in TS?

Comparing the number of pros and cons, I don't understand the purpose of TS in formik even more.

green-pickle on 1 Oct 2017

Yes, but this inevitably leads to bad code and more bugs. Types are your friend. In fact, Formik development has accelerated dramatically because of TS.

jaredpalmer on 1 Oct 2017

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@sexualmaniac Previously, I tried flow, but it didn't go well with atom. After working with typescript in formik, I'm pretty sure I won't use it again - the code looks so ugly and so dirty.

Although it probably won't happen, I also wish formik was written in regular es6, looking at typescript code makes me wanna 😭 🔫

vladshcherbin on 2 Oct 2017

@jaredpalmer the number of wrong type bugs (don't forget any typings) is very little compared to other types of bugs you'll see in a real-life app. Plus, this type checks in formik are only useful for devs, who use TS in their projects - they bring nothing to devs, who use plain js.

On the other hand, the overhead and code noise is insane - formik.tsx has almost 200 lines of code just for types - it's almost 30% of the whole file. Proper tests would serve a much better job and won't add code noise. Do you really need this overhead for formik to work well?

I highly recommend you to read this article - https://medium.com/javascript-scene/you-might-not-need-typescript-or-static-types-aa7cb670a77b, maybe it'll change your opinion on TS a bit, especially in open-source projects.

green-pickle on 3 Oct 2017

This is certainly not the place for a religious war on the merits of static-typing versus duck-typing, but I can say that @jaredpalmer and I are both fairly experienced JS developers, and after a year with the benefits of TypeScript in our projects -- the fewer tests we have to write, the clarity and self-documentation, the mistakes we catch early, the ease of sharing data models with our backend, the refactoring and autocomplete in VSCode -- I'd be very reluctant to ever go back to building anything in plain ES6.

Much of the community and many of the best companies in the space are moving in this direction also, so I don't think this is just our own weird preference. There's no accounting for taste, and use whatever works for you, but I'd recommend giving TypeScript a shot.

If it helps, just think of the types as documentation. Yes, the first ~172 lines of formik.tsx are type definitions, but most of that is comments.

My personal wish would be to get rid of the duplicative prop-types, but I think we need them to retain HOC compatibility.

eonwhite on 3 Oct 2017

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@jaredpalmer Please, keep on using Typescript.

Somehow, it makes me laugh (no offence, not targeted to any particular person in this thread) this conversation exists here, or any other place.

I disagree typings are deal breakers for contributors. Even junior members in our teams have no problem with understanding Flow typings at all.

Biggest strength of static type checkers is discovering issues without running code, so as long I/you/we discover those with TS/Flow, we should keep on using them. Removing TS would be definitely step back.

Waiting for Reason to gain more traction 😎

Andreyco on 3 Oct 2017

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@Andreyco I meant I think i can just remove these https://github.com/jaredpalmer/formik/blob/master/src/formik.tsx#L186

jaredpalmer on 3 Oct 2017

Got you. You can definitely remove them ;)

Andreyco on 3 Oct 2017

@eonwhite Thank you. Formik is the choice for many devs new to the React ecosystem (and JS for that matter), so we're grateful that it is somewhat opinionated with best practices based on your experience.