Support Asynchronous Components

Inspired by https://twitter.com/youyuxi/status/824659082816716802

It’d be great if we could do the same with Preact. Looking forward to a discussion about what would it take to add support. Off the top of my head, this would possibly need

1. Async rendering support
2. Caching of ^ so subsequent renders are immediately resolved
3. Update h to support Promises as children

A common argument against this would be to have this in userland code, however there are legitimate cases where having this baked into the framework itself would strongly encourage developers to start using code-splitting, which I think fits into Preact’s goals of performance and min size.

[robertknight]

Given that React now has an official API for loading components lazily (Suspense), perhaps we should close this issue in favour of one for implementing an API compatible with React.lazy?

[Satyam]

I would like to suggest to add the ability for componentWillMount and componentWillReceiveProps to return a Promise, in which case the rendering would be delayed until the Promise is resolved. I meant to offer a working example and I modified setComponentProps and tried to make some examples to show it working but, unfortunately, due to my lack of deep knowledge of Preact, failed to make it work.

The Readme file on the example code explains what I tried to do and how to use it.

The existing tests on the modified Preact run fine, so the change is backward compatible.

I am sorry I am new to Preact, I hoped I could be more helpful.

Thanks