jquery.linkify.js

function linkify(string, buildHashtagUrl, includeW3, target, noFollow) {
  relNoFollow = "";
  if (noFollow) {
    relNoFollow = " rel=\"nofollow\"";
  }

  if (string.toLowerCase().indexOf("www.") === 0 && includeW3) {
    string = '<a href="http://' + string + '" target="' + target + '"' + relNoFollow + '>' + string + '</a>';
  } else {
    string = '<a href="' + string + '" target="' + target + '"' + relNoFollow + '>' + string + '</a>';
  }

  if (buildHashtagUrl) {
    string = string.replace(/\B#(\w+)/g, '<a href=' + buildHashtagUrl("$1") + ' target="' + target + '"' + relNoFollow + '>#$1</a>');
  }
  return string;
}

(function($) {
  $.fn.linkify = function(opts) {
    return this.each(function() {
      var buildHashtagUrl;
      var includeW3 = true;
      var target = '_self';
      var noFollow = true;
      var regex = /((http|https|ftp)\:\/\/|\bw{3}\.)[a-z0-9\-\.]+\.[a-z]{2,3}(:[a-z0-9]*)?\/?([a-z\u00C0-\u017F0-9\-\._\?\,\'\/\\\+&amp;%\$#\=~])*/gi;
      var txt = this.innerHTML;
      var output = '';
      var replacement;
      var matchLen;
      var lastIndex = 0;

      if (opts) {
        if (typeof opts  == "function") {
          buildHashtagUrl = opts;
        } else {
          if (typeof opts.hashtagUrlBuilder == "function") {
            buildHashtagUrl = opts.hashtagUrlBuilder;
          }
          if (typeof opts.includeW3 == "boolean") {
            includeW3 = opts.includeW3;
          }
          if (typeof opts.target == "string") {
            target = opts.target;
          }
          if (typeof opts.noFollow == "boolean") {
            noFollow = opts.noFollow;
          }
        }
      }

      while ((match = regex.exec(txt)) !== null) {
        matchLen = match[0].length;
        replacement = linkify(match[0], buildHashtagUrl, includeW3, target, noFollow);
        output += txt.substring(lastIndex, match.index + matchLen).replace(match[0], replacement);
        lastIndex = match.index + matchLen;
      }

      // Include the rest of the text.
      if (lastIndex !== txt.length) {
        output += txt.substring(lastIndex);
      }

      $(this).html(output);
    });
  };
})(jQuery);