How to extract a link from a message with regular expressions?

Question

Possible Duplicate:
How to extract text from Link in Javascript?

I want to extract a hyperlink in a message. I thought it should be done by regular expressions and then surrounded with a a-tag. But how to do a regular expression that extracts a link from a message?

Here's my incomplete attempt:

var str = ' Disappointing Usability http://t.co/wkTFYhQq';
 var pattern = /http:///w{1,100}/i
 var str2 =  pattern.exec(str);
 alert(str2); 

Answer 1

Use match with this regex, that should get you an array with all links in a string:

/(?:https?|ftp|www)[^\s]+/g

Answer 2

Your pattern should capture the URL in a group:

var pattern = /(...)/;
var output = input.replace(pattern, '<a href="$1">$1</a>');

There are heaps of URL patterns available, depending on how inclusive you want to be.