[IME] Strange selection behaviour when writing before a mark

[gracicot]

Do you want to request a feature or report a bug?

Bug

What's the current behavior?

The selection is moving at the start of the inputted text/letter when writing just before a mark. It only happen on Adroid.

I tested with Chrome android and chrome keyboard.

Here's a gif:
https://imgur.com/a/MfqlnfD

Code sandbox link

With a minimal slatejs setup, we were also able to reproduce the issue.

Due to how our app is made, a mark is almost always at the end so it happens all the time, crippling text writing.

What's the expected behavior?

The selection should be stable when writing

[gracicot]

I investigated the bug, and it seem to come from the findPoint function.

When typing into the editor, android write the text into the slate-zero-width span element.

That element contains text &#65279. But the element is then discarded from the text:

Array.from(zeroWidths).forEach(function (el) {
    el.parentNode.removeChild(el);
});

The entered text is discarded and the offset is set to 0.

Later in the code, I see:

// COMPAT: If the parent node is a Slate zero-width space, this is because the
// text node should have no characters. However, during IME composition the
// ASCII characters will be prepended to the zero-width space, so subtract 1
// from the offset to account for the zero-width space character.
if (offset === node.textContent.length && parentNode.hasAttribute(DATA_ATTRS.ZERO_WIDTH)) {
    offset--;
}

But with the logic above, I don't see how that can be executed, since a zero width is contained in a span with no attribute, then contained in a slate leaf element.

[gracicot]

With further investigations, I saw that normalization also set the offset to 0.

The node returned by node.getNode(path) report no text inside.

I think the issue is because the text is entered in the wrong element inside the document. It should not write into the zero width node.

Anyway, I refer this issue: #2368 since it only happen in android.

I'm willing to give more information if necessary.

[ianstormtaylor]

I believe that this may be fixed by #3093, which has changed a lot of the logic in Slate and slate-react especially. I'm going to close this out, but as always, feel free to open a new issue if it persists for you. Thanks for understanding.