jsdo.it is a community site that provides frond-end engineers and web engineers with the opportunity to share their knowledge and technologies. Currently, about 42,000 front-end engineers participate in jsdo.it., and codes of over 100,000 works have been posted and shared. Besides posting and sharing of source codes, jsdo.it offers the Fork function,which allows users to rewrite source codes (works) posted by others. One source code can be developed into various derivative works.
See the official jsdo.it blog about how to use JSX and CoffeeScript on jsdo.it.