Everything in the browser eventually comes down to C/C++. But as far as I can tell controls like the Yahoo UI Rich Text Editor are implemented in pure Javascrip

Everything in the browser eventually comes down to C/C++. But as far as I can tell controls like the Yahoo UI Rich Text Editor are implemented in pure Javascript. And by this I mean it modifies the DOM in Javascript (and the browser handles rendering the updated DOM) as opposed to using browser magic (like an ActiveX control in IE). If I'm wrong, could someone please point me to documentation explaining exactly how these RTE's are implemented?