I expect zero width spaces to have the same effect as regular spaces regarding wrapping text. However, in Safari, lines are not broken at zero width spaces. This is different to Chrome and Firefox, which break lines on zero width spaces when wrapping. https://codesandbox.io/s/wrapping-japanese-with-zwsp-f1nuic?file=/index.html
My use case for this functionality was to allow my japanese strings to indicate appropriate spots to break lines without creating space between characters.
Thank you for filing this bug report. It looks like zero-width space is not treated as a soft wrap opportunity when "word-break: keep-all" is set on the block container.
<rdar://problem/102593988>
Created attachment 463656 [details] [fast-cq]Patch
Created attachment 463657 [details] screen-shot of the test case with the patch applied
Committed 256937@main (d97fdbd62db3): <https://commits.webkit.org/256937@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 463656 [details].
Wow! I'm glad I could create a good bug report and it was addressed so quickly!
(In reply to Mark Donnellon from comment #7) > Wow! I'm glad I could create a good bug report and it was addressed so > quickly! I wish all bug reports were like this :) Thanks again!