Wrap with an <a> element all the mention occurrences in a string.

test_if_mention.js

test_if_mention : function(string) {
  var thestring=string;
  var pattern = /@([a-zA-Z0-9_]+)/g;
  return thestring.replace(pattern, "<a href='http://twitter.com/$1' target='_blank'>@$1</a>");
}