I ask trepidatiously as there is probably a simple obvious solution somewhere, but given that haxe has conditional statements to allow for compiling to multiple environments, how is it that you make a single project compile to both flash and javascript? I feel I should be able to answer this myself, but I have yet to find an example.
The screenshot below is the project creation dialog:

I’m only able to select on type of project. I see the “empty project” option, is that where this is done? Or is there a way to share classes across projects?
I’m using flash develop 4 and plain haxe (not nme). I haven’t used flashdevelop in several years, so I realize this may be a flashdevelop question and not a haxe quesion.
Create an AS3 project, then duplicate the .hxproj file: now you have 2 projects in the same location sharing the same code.
Open this new .hxproj, go in Project properties and change the target to Actionscript and the output to some
as3folder instead of “app.swf”.