JavaScript regex whitespace characters

Question

I have done some searching, but I couldn't find a definitive list of whitespace characters included in the \s in JavaScript's regex.

I know that I can rely on space, line feed, carriage return, and tab as being whitespace, but I thought that since JavaScript was traditionally only for the browser, maybe URL encoded whitespace and things like   and %20 would be supported as well.

What exactly is considered by JavaScript's regex compiler? If there are differences between browsers, I only really care about webkit browsers, but it would be nice to know of any differences. Also, what about Node.js?

Jack G · Accepted Answer · 2022-07-16 20:16:28Z

11

A simple test:

for(var i = 0; i < 1114111; i++) {
    if(String.fromCodePoint(i).replace(/\s+/, "") == "") console.log(i);
}

The char codes (Chrome):

edited Jul 16, 2022 at 20:16

Jack G

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answered May 20, 2011 at 14:52

pimvdb

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Alex K. · Accepted Answer · 2011-05-20 14:53:29Z

7

For Mozilla its;

 [ \f\n\r\t\v\u00A0\u2028\u2029]

(Ref)

For IE (JScript) its

[ \f\n\r\t\v]

(Ref)

answered May 20, 2011 at 14:53

Alex K.

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1 Comment

Alex K. Over a year ago

FF looks like it does, for IE instead of \s use the class [\s\u00A0\u2028\u2029]

pimvdb · Accepted Answer · 2011-05-20 14:54:31Z

3

HTML != Javascript. Javascript is completely literal, %20 is %20 and   is a string of characters & n b s p and ;. For character classes I consider nearly every that is RegEx in perl to be applicable in JS (you can't do named groups etc).

http://www.regular-expressions.info/javascript.html is the refernece I use.

edited May 20, 2011 at 14:54

pimvdb

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answered May 20, 2011 at 14:53

Kinlan

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2 Comments

beatgammit Over a year ago

Right, but JavaScript often runs in the browser, so I assumed that there might be some special cases.

beatgammit Over a year ago

I'm marked yours as correct because you cleared up the root question. Thanks!

jsejcksn · Accepted Answer · 2020-10-18 10:58:47Z

Here's an expansion of primvdb's answer, covering the entire 16-bit space, including unicode code point values and a comparison with str.trim(). I tried to edit the answer to improve it, but my edit was rejected, so I had to post this new one.

Identify all single-byte characters which will be matched as whitespace regex \s or by String.prototype.trim():

const regexList = [];
const trimList = [];

for (let codePoint = 0; codePoint < 2 ** 16; codePoint += 1) {
  const str = String.fromCodePoint(codePoint);
  const unicode = codePoint.toString(16).padStart(4, '0');

  if (str.replace(/\s/, '') === '') regexList.push([codePoint, unicode]);
  if (str.trim() === '') trimList.push([codePoint, unicode]);
}

const identical = JSON.stringify(regexList) === JSON.stringify(trimList);
const list = regexList.reduce((str, [codePoint, unicode]) => `${str}${unicode} ${codePoint}\n`, '');

console.log({identical});
console.log(list);

The list (in V8):

Scherbius.com · Accepted Answer · 2011-05-20 14:57:33Z

1

In Firefox \s - matches a single white space character, including space, tab, form feed, line feed. Equivalent to [ \f\n\r\t\v\u00A0\u2028\u2029].

For example, /\s\w*/ matches ' bar' in "foo bar."

https://developer.mozilla.org/en/JavaScript/Guide/Regular_Expressions

answered May 20, 2011 at 14:57

Scherbius.com

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