HTML auto closing tag is not undoable

[masad-frost]

Describe the issue

When you type <div> HTML completes it with <div></div> which is nice, but sometimes you don't want that, does it make sense to mark </div>

Happy to send a change for this, but wanted to check if @marijnh agrees conceptually.

Change would involve adding https://codemirror.net/docs/ref/#commands.isolateHistory to this transaction https://github.com/codemirror/lang-html/blob/e7551faba95ea84e4f6bbc53bcd567d351777d55/src/html.ts#L187 which would add a dependency on @codemirror/commands in @codemirror/lang-html.

Browser and platform

any

Reproduction link

https://codemirror.net/try/?c=aW1wb3J0IHtiYXNpY1NldHVwLCBFZGl0b3JWaWV3fSBmcm9tICJjb2RlbWlycm9yIgppbXBvcnQge2h0bWx9IGZyb20gIkBjb2RlbWlycm9yL2xhbmctaHRtbCIKCm5ldyBFZGl0b3JWaWV3KHsKICBkb2M6ICI8ZGl2IiwKICBleHRlbnNpb25zOiBbYmFzaWNTZXR1cCwgaHRtbCh7CiAgICBhdXRvQ2xvc2VUYWdzOiB0cnVlCiAgfSldLAogIHBhcmVudDogZG9jdW1lbnQuYm9keQp9KQo=

[marijnh]

I don't think it's that simple. That transaction inserts both the > and the </div>, so undoing it in isolation would still also remove the > (which is, in most cases, the current behavior). There's currently no way to mark part of a transaction as separately-undoable.

[masad-frost]

Would it make sense to do 2 transactions?

[masad-frost]

Out of curiosity, why are we using input handler here instead of transaction filter?

[marijnh]

Out of curiosity, why are we using input handler here instead of transaction filter?

Because we are looking to respond to typed input. Why would a transaction filter be better?

Anyway, doing this right required some changes to @codemirror/view (codemirror/view@baf021e, codemirror/view@0c8ccde), but those were probably a good idea anyway. Attached patch makes the HTML tag closing work like this, and codemirror/lang-javascript@b84ed85 does the same for JSX tag closing.

[masad-frost]

Not suggesting it's better, but in my mind it felt like this is something we would want to do after the view gets a chance to process the input (and any quirkiness that might come with input) and create a transaction for us. Passing the base transaction getter makes it click for me more now.

Thank you.

[marijnh]

Not suggesting it's better, but in my mind it felt like this is something we would want to do after the view gets a chance to process the input

Sometimes. But in other cases you want to do something completely different that doesn't involve the original input (such as skipping the parenthesis after the cursor in closeBrackets), so giving the handler the option to not run the default behavior seems useful.