//found at http://jmrware.com/articles/2010/linkifyurl/linkify.html

var text = "Blog: http://t.co/emr776glhd MVC–Authorize filter that loads users and roles from the application configuration file http://t.co/bbrUHOMOhb"

var url_pattern = /(\()((?:ht|f)tps?:\/\/[a-z0-9\-._~!$&'()*+,;=:\/?#[\]@%]+)(\))|(\[)((?:ht|f)tps?:\/\/[a-z0-9\-._~!$&'()*+,;=:\/?#[\]@%]+)(\])|(\{)((?:ht|f)tps?:\/\/[a-z0-9\-._~!$&'()*+,;=:\/?#[\]@%]+)(\})|(<|&(?:lt|#60|#x3c);)((?:ht|f)tps?:\/\/[a-z0-9\-._~!$&'()*+,;=:\/?#[\]@%]+)(>|&(?:gt|#62|#x3e);)|((?:^|[^=\s'"\]])\s*['"]?|[^=\s]\s+)(\b(?:ht|f)tps?:\/\/[a-z0-9\-._~!$'()*+,;=:\/?#[\]@%]+(?:(?!&(?:gt|#0*62|#x0*3e);|&(?:amp|apos|quot|#0*3[49]|#x0*2[27]);[.!&',:?;]?(?:[^a-z0-9\-._~!$&'()*+,;=:\/?#[\]@%]|$))&[a-z0-9\-._~!$'()*+,;=:\/?#[\]@%]*)*[a-z0-9\-_~$()*+=\/#[\]@%])/img;

var url_replace = '$1$4$7$10$13<a href="$2$5$8$11$14">$2$5$8$11$14</a>$3$6$9$12';

text.replace(url_pattern, url_replace);