Javascript - regex - word boundary (\b) issue

Question

I have a difficulty using \\b and greek characters in a regex.

At this example [a-zA-ZΆΈ-ώἀ-ῼ]* succeeds to mark all the words I want (both

Answer 1

Try something like this:

\s[a-zA-ZΆΈ-ώἀ-ῼ]{2}\s

Answer 2

You can use \S

Rather than write a match for "word characters plus these characters" it may be appropriate to use a regex that matches not-whitespace:

\S

It's broader in scope, but simpler to write/use.

If that's too broad - use an exclusive list rather than an inclusive list:

[^\s\.]

That is - any character that is not whitespace and not a dot. In this way it's also easy to add to the exceptions.

Don't try to use \b

Word boundaries don't work with none-ascii characters which is easy to demonstrate:

> "yay".match(/\b.*\b/)
["yay"]
> "γaγ".match(/\b.*\b/)
["a"]

Therefore it's not possible to use \b to detect words with greek characters - every character is a matching boundary.

Match 2 character words

The following pattern can be used to match two character words:

pattern = /(^|[\s\.,])(\S{2})(?=$|[\s\.,])/g;

(More accurately: to match two none-whitespace sequences).

That is:

(^|[\s\.,]) - start of string or whitespace/punctuation (back reference 1)
(\S{2})     - two not-whitespace characters (back reference 2)
($|[\s\.,]) - end of string or whitespace/punctuation (positive lookahead)

That pattern can be used like so to remove matching words:

"input string".replace(pattern);

Here's a jsfiddle demonstrating the patterns use on the texts in the question.

Answer 3

Since Javascript doesn't have the lookbehind feature and since word boundaries work only with members of the \w character class, the only way is to use groups (and capturing groups if you want to make a replacement):

(?m)(^|[^a-zA-ZΆΈ-ώἀ-ῼ\n])([a-zA-ZΆΈ-ώἀ-ῼ]{2})(?![a-zA-ZΆΈ-ώἀ-ῼ])

example to remove 2 letters words:

txt = txt.replace(/(^|[^a-zA-ZΆΈ-ώἀ-ῼ\n])([a-zA-ZΆΈ-ώἀ-ῼ]{2})(?![a-zA-ZΆΈ-ώἀ-ῼ])/gm, '\1');