RegExp.prototype.unicode

The unicode accessor property of RegExp instances returns whether or not the u flag is used with this regular expression.

RegExp.prototype.unicode has the value true if the u flag was used; otherwise, false. The u flag enables various Unicode-related features. With the “u” flag:

Any Unicode code point escapes (u{xxxx}, p{UnicodePropertyValue}) will be interpreted as such instead of identity escapes. For example /u{61}/u matches “a”, but /u{61}/ (without u flag) matches “u”.repeat(61), where the u is equivalent to a single u. Buffer boundary assertions (A, z, Z) will be interpreted as such instead of identity escapes. Surrogate pairs will be interpreted as whole characters instead of two separate characters. For example, /[😄]/u would only match “😄” but not “ud83d”. When lastIndex is automatically advanced (such as when calling exec()), unicode regexes advance by Unicode code points instead of UTF-16 code units.