TheunicodeSets accessor property ofRegExp instances returns whether or not thev flag is used with this regular expression.

Try it

const regex1 = /[\p{Lowercase}&&\p{Script=Greek}]/;const regex2 = /[\p{Lowercase}&&\p{Script=Greek}]/v;console.log(regex1.unicodeSets);// Expected output: falseconsole.log(regex2.unicodeSets);// Expected output: true

Description

RegExp.prototype.unicodeSets has the valuetrue if thev flag was used; otherwise,false. Thev flag is an "upgrade" to theu flag that enables more Unicode-related features. ("v" is the next letter after "u" in the alphabet.) Becauseu andv interpret the same regex in incompatible ways, using both flags results in aSyntaxError. With thev flag, you get all features mentioned in theu flag description, plus:

• The\p escape sequence can be additionally used to match properties of strings, instead of just characters.
• Thecharacter class syntax is upgraded to allow intersection, union, and subtraction syntaxes, as well as matching multiple Unicode characters.
• The character class complement syntax[^...] constructs a complement class instead of negating the match result, avoiding some confusing behaviors with case-insensitive matching. For more information, seeComplement classes and case-insensitive matching.

Some validu-mode regexes become invalid inv-mode. Specifically, the character class syntax is different and some characters can no longer appear literally. For more information, seev-mode character class.

The set accessor ofunicodeSets isundefined. You cannot change this property directly.

Examples

Using the unicodeSets property

const regex = /[\p{Script_Extensions=Greek}&&\p{Letter}]/v;console.log(regex.unicodeSets); // true

Specifications

Browser compatibility

See also

• RegExp.prototype.lastIndex
• RegExp.prototype.dotAll
• RegExp.prototype.global
• RegExp.prototype.hasIndices
• RegExp.prototype.ignoreCase
• RegExp.prototype.multiline
• RegExp.prototype.source
• RegExp.prototype.sticky
• RegExp.prototype.unicode
• RegExp v flag with set notation and properties of strings on v8.dev (2022)