Update loading state of jetpack magic login in better way

[CodeyGuyDylan]

Proposed Changes

• Use state variable that is updated by Login form rather than a class variable updated by the parent

Why are these changes being made?

• The way this was handled before with a class variable that was updated directly on componentDidMount is not usually how these types of things are done in React.
• The update, while is still essentially a check to see if the component has mounted, makes it so we do so through react state updates instead to make it more unified in its approach to state updates with the rest of the class

Testing Instructions

1. Start a Jurassic Ninja site with Bleeding edge checked out
2. Go to /wp-admin/admin.php?page=my-jetpack#/onboarding on the site
3. Fill out your email and submit the form
   
4. When you are sent to the loading page, you will see the flashes that were reported
5. Start up your local Calypso environment (or use the live link) and replace the domain in the URL. Reload the page and you should see a loading indicator until the email was sent

loading-state.mov

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
  • For UI changes, have we tested the change in various languages (for example, ES, PT, FR, or DE)? The length of text and words vary significantly between languages.
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-140027

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-140027&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-140027&env=a8c-for-agencies

[matticbot]

Here is how your PR affects size of JS and CSS bundles shipped to the user's browser:

App Entrypoints (~18 bytes added 📈 [gzipped])

name         parsed_size           gzip_size
entry-login       +102 B  (+0.0%)      +18 B  (+0.0%)

Common code that is always downloaded and parsed every time the app is loaded, no matter which route is used.

Legend

What is parsed and gzip size?

Parsed Size: Uncompressed size of the JS and CSS files. This much code needs to be parsed and stored in memory.
Gzip Size: Compressed size of the JS and CSS files. This much data needs to be downloaded over network.

Generated by performance advisor bot at iscalypsofastyet.com.

[tyxla]

Isn't this more or less the same approach like the isInitialMount property was doing, but just done with a state variable?

It still feels like we're not addressing the root cause, but working around it.

Do we know the root cause and what else have we tried to resolve the issue?

[CodeyGuyDylan]

Isn't this more or less the same approach like the isInitialMount property was doing, but just done with a state variable?

It still feels like we're not addressing the root cause, but working around it.

Do we know the root cause and what else have we tried to resolve the issue?

The root cause is that any loading state variable that I could use to check to see if the form is ready defaults to false. This causes a flash on the screen until that loading variable is set to true. The reason I chose not to just change the default to true is because the flow is very complex and I have little knowledge about other uses of it, and if I were to change the default to true, I am unsure of all the places where I'd need to set it to false in the event that a certain variation of the flow doesn't need to load that data.

I could look more into it to get a more complete understanding the flow and all the variations, however I am currently the only person on my team present during these hours of the day and with the onboarding releasing today in the Jetpack release I don't currently have time to do that. I will keep it on our things to look at for i2 of the onboarding flow so hopefully we can fix the root issue later. Thank you for taking a look at this

[tyxla]

Thanks @CodeyGuyDylan!

Would be nice if we follow up on this at some point @Automattic/jetpack-martech

[grzegorz-cp]

I will look after this PR next week.

[grzegorz-cp]

@tyxla I updated the PR because there were some conflicts and I'd like to merge it tomorrow. Let me know if you have any concerns.

[matticbot]

This PR modifies the release build for the following Calypso Apps:

For info about this notification, see here: PCYsg-OT6-p2

• help-center
• notifications

To test WordPress.com changes, run install-plugin.sh $pluginSlug update/loading-state-of-jetpack-magic-login on your sandbox.

[grzegorz-cp]

I resolved conflicts after merging trunk and tested it 👍

[tyxla]

@grzegorz-cp if you read my feedback above, I did have some concerns which remained unaddressed: #102246 (comment)

[grzegorz-cp]

Thank you, we will be tracking it here