Encodes or decodes strings using Base64. Works in all modern Browsers (Chrome, Firefox, Safari, Opera), but does not work in IE.
Hint: It is simply using the not so well known btoa and atob methods.
More info: https://developer.mozilla.org/en/DOM/window.btoa
For a “real” version in exactly 140 Bytes see https://gist.github.com/989006 !