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Lack of support for applying extra spacing between Chinese/Japanese and Western text #401
Description
This issue applies to Chinese and Japanese.
In Chinese and Japanese composition, it is usually recommended to apply extra spacing between Chinese/Japanese han/kana characters and certain other types of text to make the text read better. The gap is typically used between han/kana characters and Latin letters, numbers, or punctuation, and should be smaller than an ASCII space would be.
ASCII spaces are not only too wide, but they spoil the semantics and behaviour of the text.
More:
The GAP (original text)
Currently, browsers do not support this feature, so content authors have to work around the problem by adding spaces manually, but because this produces too wide spaces and inserts characters that are not appropriate into the text, many texts don't have any gap between these runs of text.
In the css-text specification, text-autospace is intended to create 1/8em extra spacing between runs of ideographs/kana and Western letters/numerals.
In order to remediate texts where ASCII spaces have been used, the CSS text-autospace property also has a replace value, which will (without changing the underlying code points) replace the spaces with an appropriately-sized gap during the rendering of the text.
By default space should be added (the default value is normal, which is equivalent to ideograph-alpha and ideograph-numeric.)
Gecko, Blink, and Webkit browsers all fail to add the extra spacing between runs of ideographs and non-ideographic letters.
Priority
Given that, though not ideal, people have been forced to omit the gap or (worse) use ASCII spaces, this is prioritised as an advanced issue, however this is really a basic feature of Chinese/Japanese text, and so needs to be addressed.
Tests & results
Action taken
Bug reports: Gecko 1 • Gecko 2 • Blink 1 • Blink 2 • WebKit 1 • WebKit 2 • WebKit 3
GH issues: spacing
Outcomes
As of version 18.4 WebKit browsers now support text-autospace: ideograph-alpha|ideograph-numeric, but they don't yet support the replace keyword. This is problematic because, many websites currently use a space to separate these items, even though it is not ideal.
WebKit also applies no-autospace as the default, contrary to the CSS spec, which expects the value to be normal. There is an ongoing discussion about whether the default behaviour should add or not add gaps.
Gecko is considering support but it is not yet available.
The Blink issue has been marked as fixed on Jul 10, 2025. It is not yet available on Blink browsers.
Unicode proposal: EAST ASIAN AUTO SPACING (Proposal)
| text-autospace | Blink | Gecko | WebKit |
|---|---|---|---|
| ideograph-alpha | ❌ | ❌ | ✅ |
| ideograph-numeric | ❌ | ❌ | ✅ |
| replace | ❌ | ❌ | ❌ |
Activity
xfq commentedon Oct 17, 2021
The first comment in this issue contains text that will automatically appear in one or more gap-analysis documents as a subsection with the same title as this issue. Any edits made to that comment will be immediately available in the document. Proposals for changes or discussion of the content can be made in comments below this point.
Relevant gap analysis documents include:
Chinese • Japanese
xfq commentedon Oct 17, 2021
macnmm commentedon Oct 18, 2021
The main problem with the workaround is the lack of control in how the widths of these spaces are adjusted. For Japanese spacing, the space glyph in whatever font is likely too wide and doesn't collapse correctly when the line is compressed. For Korean, the space character is always input for word spaces, but again the width is not correct and not contextually controllable (Latin-K versus K-K can be different).
r12a commentedon Oct 19, 2021
r12a commentedon Oct 19, 2021
r12a commentedon Oct 19, 2021
Btw, i think this issue probably also applies to Thai and other scripts that don't use space as a word-separator, not just C&J. And you should probably create a stub, pointing here for the Japanese gap-analysis doc, so that we don't end up duplicating work.
xfq commentedon Oct 20, 2021
xfq commentedon Oct 20, 2021
xfq commentedon Oct 20, 2021
I did consider Thai at the time of writing, but because Thai do use spaces (although not as a word-separator), I didn’t write it. If you are sure that Thai also has this requirement, I can write it in this issue. Or should I create a sealreq issue?
3 remaining items
xfq commentedon Mar 27, 2023
I updated the links to reflect the refactoring of text-spacing in Feb 2023.
xfq commentedon Oct 16, 2023
Added a link to another Chromium issue.
xfq commentedon Oct 16, 2023
Added a link to another WebKit issue.
xfq commentedon Jul 1, 2024
There is also a proposal in Unicode related to this: v1 v2 v3
xfq commentedon Dec 19, 2024
Safari added support for the
text-autospaceproperty in Technology Preview 210: https://webkit.org/blog/16406/release-notes-for-safari-technology-preview-210/xfq commentedon Apr 3, 2025
See also https://developer.apple.com/documentation/safari-release-notes/safari-18_4-release-notes#CSS and WebKit/WebKit#40309
xfq commentedon Oct 19, 2025
The Chromium issue has been marked as fixed on Jul 10, 2025: https://issues.chromium.org/issues/40275399?pli=1
xfq commentedon Oct 20, 2025
The
text-autospaceproperty has just been enabled for Firefox 145, though note that not all values are implemented yet (there's no support forreplaceat this time).duyuang commentedon Oct 20, 2025
xfq commentedon Oct 22, 2025