Javascript reg ex to match whole word only, bound only by whitespace.

Question

Hi, so I know \bBlah\b will match a whole Blah, however it will also match Blah in "Blah.jpg" I don't want it to. I want to match only whole words with a space on either side.

Answer 1

Try \sBlah\s — that will match any form of whitespace on either side.

Answer 2

You can try: \sBlah\s.

Or if you allow beginning and end anchors, (^|\s)Blah(\s|$)

This will match "Blah" by itself, or each Blah in "Blah and Blah"

See also

• regular-expressions.info/Character classes and Anchors
  • \s stands for "whitespace character".
  • The caret ^ matches the position before the first character in the string
  • Similarly, $ matches right after the last character in the string

---

Lookahead variant

If you want to match both Blah in "Blah Blah", then since the one space is "shared" between the two occurrences, you must use assertions. Something like:

(^|\s)Blah(?=\s|$)

See also

• regular-expressions.info/Lookarounds

---

Capturing only Blah

The above regex would also match the leading whitespace.

If you want only Blah, ideally, lookbehind would've been nice:

(?<=^|\s)Blah(?=\s|$)

But since Javascript doesn't support it, you can instead write:

(?:^|\s)(Blah)(?=\s|$)

Now Blah would be captured in \1, with no leading whitespace.

See also

• regular-expressions.info/Grouping and flavor comparison

Answer 3

(^|\s)Blah(\s|$) should work, however it will also select the spaces, if you just want the word you can do this: (^|\s)(Blah)(\s|$) and take group 2 ($2 in ruby).

If want help with a RegEx, checkout: http://www.gskinner.com/RegExr/