CODEWITHSUNDEEP
javascriptregex
doorman
doorman

Reputation: 16959

Getting matches from XRegExp

Using XRegExp I have the following regex to match words that start with uppercase letters:

var regex = XRegExp("/\p{Ll}*\p{Lu}+\p{Ll}*/gu");
var matches = XRegExp.exec("TestString", regex);

However the matches variable is always null. I am not sure if the regex is wrong or if I am using xregexp incorrectly. How can I get matches for words that start with uppercase letters?

Upvotes: 1

Views: 358

Answers (2)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 627022

You can use XRegExp.match with the scope set to all/g modifer, or run XRegExp.exec in a loop:

var regex = XRegExp("\\p{Ll}*\\p{Lu}+\\p{Ll}*");
// Or: const regex = XRegExp(String.raw`\p{Ll}*\p{Lu}+\p{Ll}*`); 
var matches = XRegExp.match("TestString", regex, "all");
console.log(matches);

var regex1 = XRegExp("\\p{Ll}*\\p{Lu}+\\p{Ll}*", "g");
var results=[], match;
XRegExp.forEach("TestString", regex1, function (match, i) {
    results.push(match[0]);
});
console.log(results);
<script src="https://cdnjs.cloudflare.com/ajax/libs/xregexp/3.2.0/xregexp-all.min.js"></script>

NOTE:

  • Double the backslashes, or use String.raw notation with single backslashes in the string literal
  • Do not use regex delimiters when defining the XRegExp patterns defined with string literals
  • u modifier does not make sense here, unless you want to support ES6 regex features like \u{XXXX} and . matching any Unicode code point
  • g can be overridden with all as the scope value.

See XRegExp.match(str, regex, [scope]):

Returns the first matched string, or in global mode, an array containing all matched strings. This is essentially a more convenient re-implementation of String.prototype.match that gives the result types you actually want (string instead of exec-style array in match-first mode, and an empty array instead of null when no matches are found in match-all mode). It also lets you override flag g and ignore lastIndex, and fixes browser bugs.

And its scope parameter:

Use 'one' to return the first match as a string. Use 'all' to return an array of all matched strings. If not explicitly specified and regex uses flag g, scope is all.

Upvotes: 2

The fourth bird
The fourth bird

Reputation: 163437

According to the examples in the documentation, you can double escape the backslash and the flags is the second parameter.

XRegExp(pattern, [flags])

The value of pattern can be {String|RegExp} so you could use it like this using String

var regex = XRegExp("\\p{Ll}*\\p{Lu}+\\p{Ll}*", "gu");
var matches = XRegExp.match("TestString", regex);
console.log(matches);
<script src="https://cdnjs.cloudflare.com/ajax/libs/xregexp/3.2.0/xregexp-all.min.js"></script>

Or use it like this using a RegExp

var regex = XRegExp(/\p{Ll}*\p{Lu}+\p{Ll}*/gu);
var matches = XRegExp.match("TestString", regex);
console.log(matches);
<script src="https://cdnjs.cloudflare.com/ajax/libs/xregexp/3.2.0/xregexp-all.min.js"></script>

Upvotes: 2

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