XRegExp provides augmented (and extensible) JavaScript regular expressions. You get modern syntax and flags beyond what browsers support natively. XRegExp is also a regex utility belt with tools to make your grepping and parsing easier, while freeing you from regex cross-browser inconsistencies and other annoyances.
XRegExp supports all native ES6 regular expression syntax. It supports ES5+ browsers, and you can use it with Node.js or as a RequireJS module.
Performance
XRegExp compiles to native RegExp objects. Therefore regexes built with XRegExp perform just as fast as native regular expressions. There is a tiny extra cost when compiling a pattern for the first time.
Usage examples
// Using named capture and flag x for free-spacing and line commentsconstdate=XRegExp(`(?<year> [0-9]{4} ) -? # year (?<month> [0-9]{2} ) -? # month (?<day> [0-9]{2} ) # day`,'x');// XRegExp.exec gives you named backreferences on the match resultlet match =XRegExp.exec('2017-02-22', date);match.year; // -> '2017'// It also includes optional pos and sticky argumentslet pos =3;constresult= [];while (match =XRegExp.exec('<1><2><3>4<5>', /<(\d+)>/, pos,'sticky')) {result.push(match[1]); pos =match.index + match[0].length;}// result -> ['2', '3']// XRegExp.replace allows named backreferences in replacementsXRegExp.replace('2017-02-22', date,'$<month>/$<day>/$<year>');// -> '02/22/2017'XRegExp.replace('2017-02-22', date, (match) => {return`${match.month}/${match.day}/${match.year}`;});// -> '02/22/2017'// XRegExps compile to RegExps and work perfectly with native methodsdate.test('2017-02-22');// -> true// The only caveat is that named captures must be referenced using// numbered backreferences if used with native methods'2017-02-22'.replace(date,'$2/$3/$1');// -> '02/22/2017'// Use XRegExp.forEach to extract every other digit from a stringconstevens= [];XRegExp.forEach('1a2345', /\d/, (match, i) => {if (i %2) evens.push(+match[0]);});// evens -> [2, 4]// Use XRegExp.matchChain to get numbers within <b> tagsXRegExp.matchChain('1 <b>2</b> 3 <B>4 \n 56</B>', [XRegExp('(?is)<b>.*?</b>'),/\d+/]);// -> ['2', '4', '56']// You can also pass forward and return specific backreferencesconsthtml=`<a href="http://xregexp.com/">XRegExp</a> <a href="http://www.google.com/">Google</a>`;XRegExp.matchChain(html, [ {regex: /<a href="([^"]+)">/i, backref:1}, {regex:XRegExp('(?i)^https?://(?<domain>[^/?#]+)'), backref:'domain'}]);// -> ['xregexp.com', 'www.google.com']// Merge strings and regexes, with updated backreferencesXRegExp.union(['m+a*n', /(bear)\1/, /(pig)\1/],'i', {conjunction:'or'});// -> /m\+a\*n|(bear)\1|(pig)\2/i
These examples give the flavor of what's possible, but XRegExp has more syntax, flags, methods, options, and browser fixes that aren't shown here. You can also augment XRegExp's regular expression syntax with addons (see below) or write your own. See xregexp.com for details.
Addons
You can either load addons individually, or bundle all addons with XRegExp by loading xregexp-all.js from https://unpkg.com/xregexp/xregexp-all.js.
Unicode
If not using xregexp-all.js, first include the Unicode Base script and then one or more of the addons for Unicode blocks, categories, properties, or scripts.
Then you can do this:
// Test the Unicode category L (Letter)constunicodeWord=XRegExp('^\\pL+$');unicodeWord.test('Русский'); // -> trueunicodeWord.test('日本語'); // -> trueunicodeWord.test('العربية'); // -> true// Test some Unicode scriptsXRegExp('^\\p{Hiragana}+$').test('ひらがな'); // -> trueXRegExp('^[\\p{Latin}\\p{Common}]+$').test('Über Café.'); // -> true
By default, \p{…} and \P{…} support the Basic Multilingual Plane (i.e. code points up to U+FFFF). You can opt-in to full 21-bit Unicode support (with code points up to U+10FFFF) on a per-regex basis by using flag A. This is called astral mode. You can automatically add flag A for all new regexes by running XRegExp.install('astral'). When in astral mode, \p{…} and \P{…} always match a full code point rather than a code unit, using surrogate pairs for code points above U+FFFF.
// Using flag A to match astral code pointsXRegExp('^\\pS$').test('💩'); // -> falseXRegExp('^\\pS$','A').test('💩'); // -> trueXRegExp('(?A)^\\pS$').test('💩'); // -> true// Using surrogate pair U+D83D U+DCA9 to represent U+1F4A9 (pile of poo)XRegExp('(?A)^\\pS$').test('\uD83D\uDCA9'); // -> true// Implicit flag AXRegExp.install('astral');XRegExp('^\\pS$').test('💩'); // -> true
Opting in to astral mode disables the use of \p{…} and \P{…} within character classes. In astral mode, use e.g. (\pL|[0-9_])+ instead of [\pL0-9_]+.
XRegExp uses Unicode 13.0.0.
XRegExp.build
Build regular expressions using named subpatterns, for readability and pattern reuse:
Named subpatterns can be provided as strings or regex objects. A leading ^ and trailing unescaped $ are stripped from subpatterns if both are present, which allows embedding independently-useful anchored patterns. {{…}} tokens can be quantified as a single unit. Any backreferences in the outer pattern or provided subpatterns are automatically renumbered to work correctly within the larger combined pattern. The syntax ({{name}}) works as shorthand for named capture via (?<name>{{name}}). Named subpatterns cannot be embedded within character classes.
XRegExp.tag (included with XRegExp.build)
Provides tagged template literals that create regexes with XRegExp syntax and flags:
consth12= /1[0-2]|0?[1-9]/;consth24= /2[0-3]|[01][0-9]/;consthours=XRegExp.tag('x')`${h12} : | ${h24}`;constminutes= /^[0-5][0-9]$/;// Note that explicitly naming the 'minutes' group is required for named backreferencesconsttime=XRegExp.tag('x')`^ ${hours} (?<minutes>${minutes}) $`;time.test('10:59'); // -> trueXRegExp.exec('10:59', time).minutes; // -> '59'
XRegExp.tag does more than just basic interpolation. For starters, you get all the XRegExp syntax and flags. Even better, since XRegExp.tag uses your pattern as a raw string, you no longer need to escape all your backslashes. And since it relies on XRegExp.build under the hood, you get all of its extras for free. Leading ^ and trailing unescaped $ are stripped from interpolated patterns if both are present (to allow embedding independently useful anchored regexes), interpolating into a character class is an error (to avoid unintended meaning in edge cases), interpolated patterns are treated as atomic units when quantified, interpolated strings have their special characters escaped, and any backreferences within an interpolated regex are rewritten to work within the overall pattern.
XRegExp.matchRecursive
Match recursive constructs using XRegExp pattern strings as left and right delimiters:
