What steps will reproduce the problem?
1. Open the attached html file.
2. Check textInput checkbox
3. Input something with IME in the first input element.
What is the expected output? What do you see instead?
Nothing should be inputted. But instead, some selected text is inputted.
Please use labels and text to provide additional information.
The reason of this issue:
When inputting with IME, the textInput event is generated when confirming
the composition text, but before that, the text is already inputted into the
input element as composition text (selected text). So if textInput is
prevented, then the composition text will never be confirmed.
The correct behavior should be: if textInput is prevented, all pending
composition text should be discarded.
See also issue 9883 .