What does the '|' (pipe character) mean in a regular expression?

Question

This regular expressioncomes from JQuery, and the | means or, but which two parts are included to choose?

/^(?:[^#<]*(<[\w\W]+>)[^>]*$|#([\w\-]*)$)/

Is it [^>]*$ | #([\w\-]*)$ or (<[\w\W]+>)[^>]*$ | #([\w\-]*)$) or something else?

Try looking at it on [regexper.com](http://www.regexper.com/#%5E(%3F%3A%5B%5E%23%3C%5D*(%3C%5B%5Cw%5CW%5D%2B%3E)%5B%5E%3E%5D*%24%7C%23(%5B%5Cw%5C-%5D*)%24)). — Chris Martin, Mar 05 '14 at 03:29

score 4 · Answer 1 · edited Apr 06 '14 at 09:00

4

Simply: x|y

Matches either x or y.

For example: /green|red/ matches green in green apple and red in red apple.

edited Apr 06 '14 at 09:00

HamZa

answered Mar 05 '14 at 03:31

This answer has been added to the [Stack Overflow Regular Expression FAQ](http://stackoverflow.com/a/22944075/2736496), under "Other". – aliteralmind Apr 10 '14 at 01:04

Andrew · Accepted Answer · 2014-03-05T04:22:47.107

3

It's [^#<]*(<[\w\W]+>)[^>]*$ and #([\w\-]*)$

Regular expression visualization

edited Mar 05 '14 at 04:22

answered Mar 05 '14 at 03:29

Andrew

Bergi · Answer 3 · 2014-03-05T03:58:11.017

2

Writing it multiline with indentation helps:

^
(?:
  [^#<]*
  (
    <
    [\w\W]+
    >
  )
  [^>]*
  $
|
  #
  (
    [\w\-]*
  )
  $
)

Your second guess is correct. The | has lower precedence than the concatenation (i.e. writing expressions after each other).

edited Mar 05 '14 at 03:58

answered Mar 05 '14 at 03:53

Bergi

xdazz · Answer 4 · 2014-03-05T03:35:38.863

0

It's [^#<]*(<[\w\W]+>)[^>]*$ or #([\w\-]*)$, and both in a non-capturing group.

/^(?:EXP)$)/ # EXP => A|B

/^(?:A|B)$)/ # A => [^#<]*(<[\w\W]+>)[^>]*$, B => #([\w\-]*)$

/^(?:[^#<]*(<[\w\W]+>)[^>]*$|#([\w\-]*)$)/

edited Mar 05 '14 at 03:35

answered Mar 05 '14 at 03:29

xdazz

4 Answers4