I've found some nice ones :-)
Yeah, you're right - it must preferably be used some JavaScript.
But also maybe in combination with ActiveX, PHP, asp or something.
But here are some very useful links :-)
http://www.unica.edu/uicfreesoft/
https://sourceforge.net/projects/richtext
Both are free (GPL og GPL Lesser). Think you'll get what you need here :-)
I can dig out some more links if you're interested, I haven't got them right now, but let me know if you need them.