Boa syntax checking on the fly

[psybers]

It is possible to have a Javascript based parser that at the very least does syntax checking while the user types and immediately shows the results. This would help avoid submitting bad code, waiting a few seconds for the compile, then realizing the problem.

For some of the simpler semantic checks, this may also be possible.

For reference, the JavaScript mode in Ace has such functionality:

https://github.com/ajaxorg/ace/blob/master/lib/ace/mode/javascript_worker.js
https://github.com/ajaxorg/ace/blob/master/lib/ace/mode/javascript/jshint.js