SyntaxError in a regex

Question

i found a regex that look for matching url here : http://daringfireball.net/2010/07/improved_regex_for_matching_urls, the regex is :

(?i)\b((?:https?://|www\d{0,3}[.]|[a-z0-9.\-]+[.][a-z]{2,4}/)(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*\)|[^\s`!()\[\]{};:'".,<>?«»“”‘’]))

but when i try to use it in my js file firebug shows me SyntaxError: syntax error exactly in this part (?i)

i use the regex like the following :

text = $('textarea').val();
url_regex = (?i)\b((?:https?://|www\d{0,3}[.]|[a-z0-9.\-]+[.][a-z]{2,4}/)(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*\)|[^\s`!()\[\]{};:'".,<>?«»“”‘’]));
match = url_regex.exec(text);

where is the problem please ?

Did you copy and paste that line directly into your js, or is there some more code around it? — Jongware
– Jongware, Commented Nov 16, 2013 at 3:39
stackoverflow.com/questions/15145659/… explains (?i) turns off case sensitivity (?-1) turns case sensitivity back on. — otherDewi
– otherDewi, Commented Nov 16, 2013 at 3:40
i update my question, i copy and paste the line without modification, then assign it to url_regex variable — medBouzid
– medBouzid, Commented Nov 16, 2013 at 3:41
You need to add delimiters to your pattern. Wrap it in / characters to tell Javascript it's a regex. — user1864610
– user1864610, Commented Nov 16, 2013 at 3:41
Your regex needs to be fenced by /../ -- see developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… — Jongware
– Jongware, Commented Nov 16, 2013 at 3:41

Robin · Accepted Answer · 2013-11-16 04:27:50Z

2

In javascript, regular expressions are wrapped in /s. Also, the (?i) part needs to be replaced with a i at the end to make the regex case insensitive.

text = $('textarea').val();
url_regex=/\b((?:https?:\/\/|(www\d{0,3}[.])?|[a-z0-9.\-]+[.][a-z]{2,4}\/)(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*\)|[^\s`!()\[\]{};:'".,<>?«»“”‘’]))/i
match = url_regex.exec(text);

So, as others have said, there are some differences between regex in javascript and perl.

edited Nov 16, 2013 at 4:27

answered Nov 16, 2013 at 4:02

Robin

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4 Comments

medBouzid Over a year ago

thank you @SuperScript it works now :) just one question, can i render "www" optional ?

medBouzid Over a year ago

there is some error in your comment code when i copy past it !! if i understand i need just change this part : (www\d{0,3}[.])? , but it doesn't work without www

Robin Over a year ago

I've edited it into my answer. Just re-copy the regex there.

medBouzid Over a year ago

now with this modification it works without www but problem if i put some text before url it doesn't work !! before changes it works even with text first

regulus · Accepted Answer · 2013-11-16 03:57:54Z

1

Regular expression needs to be wrapped in forward slashes and all forward slashes in it needs to be escaped with a back slash. Second (?i) is a flag to turn on case insensitive mode I guess it's for Perl but not supported in Javascript in the same way.

/\b((?:https?:\/\/|www\d{0,3}[.]|[a-z0-9.\-]+[.][a-z]{2,4}\/)(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*\)|[^\s`!()\[\]{};:\'\".,<>?«»“”‘’]))/

Should work. Also if you want to turn case insensitive mode you should use like this:

new RegExp('.*', 'i');

answered Nov 16, 2013 at 3:57

regulus

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