Editorial: Mention the special status of U+0085 NEXT LINE #3303
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It is the only character that has property "White_Space" but is not matched by either |WhiteSpace| or |LineTerminator|.
| @@ -16371,7 +16371,7 @@ <h1>White Space</h1> | |||
| <p>U+0020 (SPACE) and U+00A0 (NO-BREAK SPACE) code points are part of <USP>.</p> | |||
| </emu-note> | |||
| <emu-note> | |||
| <p>Other than for the code points listed in <emu-xref href="#table-white-space-code-points"></emu-xref>, ECMAScript |WhiteSpace| intentionally excludes all code points that have the Unicode “White_Space” property but which are not classified in general category “Space_Separator” (“Zs”).</p> | |||
| <p>Other than the code points listed in <emu-xref href="#table-white-space-code-points"></emu-xref>, ECMAScript |WhiteSpace| intentionally excludes all code points that have the Unicode “White_Space” property but which are not classified in general category “Space_Separator” (“Zs”). As of Unicode 15.1.0, the only such code point that is not a <emu-xref href="#sec-line-terminators">line terminator</emu-xref> is U+0085 (NEXT LINE).</p> | |||
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The editor group wasn't happy with this change as-is. If we really wanted to add something for the readers who might be already familiar with Unicode's White_Space property who may be confused, we can say something like
| <p>Other than the code points listed in <emu-xref href="#table-white-space-code-points"></emu-xref>, ECMAScript |WhiteSpace| intentionally excludes all code points that have the Unicode “White_Space” property but which are not classified in general category “Space_Separator” (“Zs”). As of Unicode 15.1.0, the only such code point that is not a <emu-xref href="#sec-line-terminators">line terminator</emu-xref> is U+0085 (NEXT LINE).</p> | |
| <p>Other than the code points listed in <emu-xref href="#table-white-space-code-points"></emu-xref>, ECMAScript |WhiteSpace| intentionally excludes all code points that have the Unicode “White_Space” property but which are not classified in general category “Space_Separator” (“Zs”), such as all <emu-xref href="#table-line-terminator-code-points">line terminators</emu-xref>, U+0085 (NEXT LINE), and possibly others.</p> |
But that's also probably not a significant population of readers, so it's also okay to not add anything here. Closing for now.
The link is good, but I still think an explicit mention of U+0085 (NEXT LINE) and probably also U+FEFF (ZERO WIDTH NO-BREAK SPACE) would be better. As observed in tc39/proposal-regexp-v-flag#37, the classification of these two code points is easy to overlook, and IMO it behooves the spec to highlight that. |
It is the only character that has property "White_Space" but is not matched by either |WhiteSpace| or |LineTerminator|, which leads to issues such as tc39/proposal-regexp-v-flag#37 .
Similarly, we might also consider documenting the special status of U+FEFF ZERO WIDTH NO-BREAK SPACE as the only character matched by |WhiteSpace| that does not have property "White_Space".