Javascript file writing

[wxdqz]

Is is possible, using java/javascript, to write a file, such as an html file from the website, on the client end. I have full FTP access, if that matters.
I want to have people be able to type text into a textbox and then click a button, then have it write that file to the web directory. (File type does not matter)

Thanks in advance,
~ Pepe ~