Composition API in-depth guide

[NataliaTepluhina]

We already have Composition API basics document (thanks @shentao !) but we also need to have an in-depth guide similar to what we have for Components In-Depth. While working on it, we could move part of the descriptions from Composition API reference and Reactivity APIs as they're waaaay too detailed for API reference.

Here is a rough structure of the section:

• setup()
  • props and context as setup() parameters
• Reactive state with ref and reactive
  • Template refs
  • Destructuring reactive to refs
• Computed and watchers (maybe we'd need to split this to separate chapters as watchers will contain a lot of info)
• Lifecycle hooks
• Provide/inject in the Composition API

Please keep in mind this is very rough draft and I would be happy to add any fixes/improvements to it

[NataliaTepluhina]

cc @bencodezen @shentao

[kiaking]

Lifecycle Hooks

I think it's worth mentioning about lifecycle hook usage, and describe how magically it works inside setup hook. The name are bit different than option API too.

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Reactivity Utilities

I think it would be nice to have section for Reactivity Utilities and Advanced Reactivity APIs.

I think these are too detailed to include in section such as "Reactive state with ref and reactive", so it might be nice to have separate section after "Provide/inject in the Composition API"?

Or maybe those are going to be listed in API reference, and have link in the each section...? (like "learn more advanced usage at page".

[NataliaTepluhina]

@kiaking thanks! Lifecycle hooks added

Utilities and Advanced APIs mentioned in the API Reference . Do you think it's worth adding a section covering Advanced use-cases to guide too?

[kiaking]

Roger about APIs mentioned in API Reference.

Do you think it's worth adding a section covering Advanced use-cases to guide too?

I think it would be nice to have. But not sure if we should add those at this stage. It might also suit more at examples or cookbook. So, my opinion is not to add advanced use-cases at this stage. I think we can come back later with those 👍

[shentao]

The outline looks good to me! Will try to contribute to at least a few points.

I think that some of the Reactivity Utilities could be incorporated into the in-depth Composition API guide, but the Advanced Reactivity APIs are likely too niche to add them smoothly. Instead, I think we should just have a note in the guide when showing the unref and 'toRefs' functions (likely the most popular) that there are more utilities related to reactivity.

[bencodezen]

Thanks so much for outlining this @NataliaTepluhina. I'll take the lead on this one and let everyone know when we have a draft to review.

For anyone else who sees anything we can add to the guide, please comment on the issue and I'll be sure to track it!