Feature request: `\h` to match all "horizontal whitespace" characters

[gfscott]

In several RegExp engines, \h works as a convenience method for specifying "horizontal whitespace". For the majority of cases you can capture these type of characters with only the space and tab characters ([\t ]) but that omits edge cases related to less commonly used, non-newline whitespace characters like en space (U+2002), em space (U+2003), and thin space (U+2009).

Essentially, \h gives you a subset of \s that omits the newline characters. Having access to this flag in ECMAScript would help me write regular expressions with greater confidence that I'll capture strings even if they contain rarely used whitespace characters:

\h Language support

Not exhaustive, but this table is based on the engines available in regex101:

Language/Engine	Supported?	Behavior	Example
PCRE	✅	Success	Link
PCRE 2	✅	Success	Link
Java	✅	Success	Link
Golang	🚫	Invalid token error	Link
.NET	🚫	Invalid token error	Link
Python	🚫	Matches literal h character	Link
ECMAScript	🚫	Matches literal h character	Link

[slevithan]

\h means "hexadecimal digit" ([0-9A-Fa-f], \p{AHex}) in some other regex flavors like Oniguruma and Onigmo.