Migrate @storybook/preact to Typescript

[lonyele]

Issue: #5030

What I did

I migrated app/preact to Typescript. I've put some caveats on the comments

Thoughts

As I've looked the code, I feel like @storybook/core needs to be migrated first because react, angular, html and preact have same ClientApi that can be done from core. My plan was to migrate some of other frameworks since many of them has a same architecture, but now I'm not sure about it. What do you think of migrating other frameworks? Migrate first and refactor later? Or wait for core to be migrated first and do other frameworks?

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[lonyele]

About DeepScan

I found that h is needed in preact to wrap transpiled jsx, but DeepScan doesn't like it. It seems like there is a way to resolve this by using webpack plugins, but is it necessary?

About Travis

Travis has failed... Is it because of some actual problem or just it took too much time thus terminated?

[ndelangen]

Awesome work @lonyele ! 👏

[lonyele]

@ndelangen btw do you think migrating other frameworks now under app folder is a good thing? Just to decide what to do next

As I've looked the code, I feel like @storybook/core needs to be migrated first because react, angular, html and preact have same ClientApi that can be done from core. My plan was to migrate some of other frameworks since many of them has a same architecture, but now I'm not sure about it. What do you think of migrating other frameworks? Migrate first and refactor later? Or wait for core to be migrated first and do other frameworks?

[shilman]

@lonyele mind fixing the conflicts?

[lonyele]

@shilman done!