Brendan Eich wrote javascript in about a week. Could you write javascript in 10 weeks?

Fabrice Bellard wrote (among many things) a linux emulator in javascript. (http://bellard.org/jslinux/)

I don't know how long it took him to write, but knowing he's also doing other things (http://bellard.org/) including FFMPEG, I don't think he spent his entire career on it.