feat(gatsby-plugin-typescript): add support for optional chaining and nullish coalescing operator

[Austaras]

Description

TS 3.7 has been released which supports optional chaining and nullish operator. gastby-plugin-typescript uses babel to transform TypeScript so two plugin must be added accordingly to support these new feature

[pieh]

I think this is ok for us to use, but I do wonder if @babel/preset-typescript wouldn't be more correct place to declare those plugins?

In any case I'll do some testing and will go forward with this

[Austaras]

I think this is ok for us to use, but I do wonder if @babel/preset-typescript wouldn't be more correct place to declare those plugins?

It is. But it seems that @babel/preset-typescript insists on type striping only. So from day one, to make TypeScript transform work babel plugins for class field and jsx are needed but they are in gatsby's babel preset. Actually plugin for decorator is also needed but few people use them in react world anyway.

In this case, TSC supports every stage-3 proposal and @babel/preset-env supports everything stage-4. To make up for this difference maintenance is always needed everytime a proposal enters or leaves stage-3

[pieh]

It is. But it seems that @babel/preset-typescript insists on type striping only. So from day one, to make TypeScript transform work babel plugins for class field and jsx are needed but they are in gatsby's babel preset. Actually plugin for decorator is also needed but few people use them in react world anyway.

I would expect @babel/plugin-transform-typescript to be one that just strips types, and preset would be one that tries to make it as 1to1 to tsc as possible. In any case, I don't have enough context on this to pretend I understand all the nuance and stances that @babel need to handle, so handling it here is fine for me.

[pieh]

Thanks!