Looks for URLs in the source text and replaces them with anchor tags. If there are no links in the text, it does nothing.

anchorify.js

/**
 * Looks for URLs in the source text and replaces them with anchor
 * tags. If there are no links in the text, it does nothing.
 * 
 * @param  {String}  text  Source text.
 * 
 * @return {String}        New string with URLs in the source
 *                         text replaced with anchor tags.
 */
function anchorify(text) {
  var urlRegExp = /(https?:\/\/[^\s]+)/g;
  return text.replace(urlRegExp, function(url) {
      return anchor(url, url);
  });
}