Upgrade guide

Just upgrading my 2.0 app to 3.0 and wanted to document what’s involved for anyone else upgrading.

• Views previously used choo.view to construct HTML. Now you should use const html = require('choo/html')
• Views previously received (params, state, send) as params. They now receive (state, prev, send)
• Any references to params inside the views should now point to state.params
• Any references to the current location should now point to state.location....?
• Effects and subscriptions now have a new parameter, done, which should either be explicitly called inside your effect or passed to your final send() call
• Effects and subscriptions which call send() multiple times should nest them inside the done callback, ie:

send('foo', {...}, () => {
  send('bar', {...}, done)
})

• Reducers and effects formerly received a first parameter called action. The convention is now to call it data (optional of course)
• The data param passed to reducers and effects does not need to be an object, so you can do things like send('setTitle', 'New Title'), which can improve readability

A pretty easy upgrade. The done business is probably the only confusing part. Of course, this is just what I encountered in my app. I believe @toddself also upgraded an app recently and may have had to do other things.

[yoshuawuyts]

Gehe - yeah I think async flow is amongst the hardest compsci things out there; coupled with a half-assed explanation in the docs there’s def no need to feel silly for not getting it straight away - always happy to help! ✨

[krawaller]

@yoshuawuyts That makes a ton of sense! Feel silly for not grokking it, seems so obvious now. Thank you for your help and patience!

Creating issue for the model-route thing right away!