I have come across come code written by another developer and I can not working out what it is doing:

title.replace(/(<([^>]+)>)/ig," ")

I have come across come code written by another developer and I can not working out what it is doing:

title.replace(/(<([^>]+)>)/ig," ")

• javascript
• regex

• As @RobW pointed out, you do NOT want to rely on this regex to block script injection. – user684934 Commented Feb 25, 2012 at 14:43
• 1 Nice example why I always write down at least what a reg exp is supposed to do in a comment. – Maarten Bodewes Commented Feb 25, 2012 at 15:12

2 Answers 2

It replaces all tags (substrings on the form <...>) with a space, " ".

Here's a regexp breakdown:

• <       - a left tag
• [^>] - anything but a right tag...
• +       - ...one or more times
• >       - a right tag.

The ( and ) just surrounds the groups in the expression, which are not used anyway.

The /ig suffix says that the regex is case insensitive (pointless in this case, since the rexeg doesn't mention any letters) and global stating that all occurrences should be replaced.

Looks like it's replacing HTML start or end tags. If you ever need to parse Regex expressions or test them, here's a great site. http://myregextester.com/index.php

NODE                     EXPLANATION
----------------------------------------------------------------------
(?i-msx:                 group, but do not capture (case-insensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  (                        group and capture to \1:
----------------------------------------------------------------------
    <                        '<'
----------------------------------------------------------------------
    (                        group and capture to \2:
----------------------------------------------------------------------
      [^>]+                    any character except: '>' (1 or more
                               times (matching the most amount
                               possible))
----------------------------------------------------------------------
    )                        end of \2
----------------------------------------------------------------------
    >                        '>'
----------------------------------------------------------------------
  )                        end of \1
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------