[Feature]: Enable TypeScript exactOptionalPropertyTypes

[iamandrewluca]

Describe the feature

It would be great to have the TypeScript exactOptionalPropertyTypes option enabled.

https://www.typescriptlang.org/tsconfig/#exactOptionalPropertyTypes

https://youtu.be/krj9KCxJ5OY

Additional information

• I intend to submit a PR for this feature.
• I have already implemented and/or tested this feature.

[zernonia]

Hi @iamandrewluca ! Would love to hear what do you expect for this request ya?

[iamandrewluca]

Hi, @zernonia. I will add more details to the task later today.

The YT Video I linked explains why library authors would be better off having this enabled.
In general, the change would be that any prop marked as optional via ? should also have undefined in type explicit.

[iamandrewluca]

But maybe we are not ready for this because of these two 🤔

• Problem typing optional props with exactOptionalPropertyTypes enabled in tsconfig vuejs/core#6532
• Missing support in @vue/runtime-dom for TypeScript's --exactOptionalPropertyTypes option vuejs/core#6068

[iamandrewluca]

@zernonia after reading the issues above decided to close for now, as it seems more of a problem in the upstream (vue/vue-tsc/volar) libraries

[iamandrewluca]

Hey, @zernonia I created a PR in Vue, to add undefined to optional properties. That will only allow for native elements to pass undefined when exactOptionalPropertyTypes is enabled.

In the case of libraries, they also need to mark all their optional props with explicit undefined if they want the library to work with exactOptionalPropertyTypes enabled.

We can probably reopen this issue. I intend to create PRs to implement this.

vuejs/core#12771