Well, in theory, Scirra has covered all that ground so that the rest of us don't have to. Their standard format for making plugins- unless you're trying to implement something that's just like, extremely unusual- is very simple and straightforward. So, you wouldn't have to test it under every possible circumstance for the same reasons you wouldn't have to test a new lightbulb in every commercially-available lamp. As long as you know that the lightbulb can physically function and you don't try to use it to paint your living room or something, you should be good to go.

Essentially, all you're really doing in the add-on code is modifying a JavaScript object prototype, which is core to the language already and isn't a Scirra invention or anything. Just making functions and properties as needed, specifying whichever parameters the object will require, so on and so forth. Making the program good is the important concern; as far as I can tell, anywhere regular JavaScript code currently runs, the JSSDK plugins should also run (unless it's just a badly-written plugin on the developer's part, of course, but that's not a Construct issue).

Anything they've had to do that's very platform-specific has likely been for the purpose of getting all the JavaScript functionality working as expected where it might not historically have been implemented. But assuming that's been completed successfully, there's not a whole lot of JS you could write that won't run on whatever platforms Construct will currently export to.

The only exceptions to this that I can think of are very framework-dependent applications. But even then, all you'd have to do is include whatever script-files or libraries your thing depends on inside the project file... Or, in the case that someone is wanting to develop for a platform that isn't capable of running JS programs, it's a pretty safe bet that Construct is the wrong tool. Apparently there's also some minification issues, but that's not technically necessary, and although inconvenient, doesn't restrict what you can actually do.

A few days ago I started getting the ball rolling on a plugin for Construct2 that (hopefully!) will allow you to create ReactJS apps within your Construct projects. I feel pretty strongly that Construct has some potentially awesome applications in non-gamedev projects too, and I'm just wondering if anybody else would seriously be into that, and/or into using React with Construct?

Also, more importantly, do any of you guys have feature requests for the plugin? Or any ideas on how to make it as awesome as possible, or even just about things I should definitely try to avoid?

I'm keeping the feature-set a tad basic for starters... It'll be a while before I get around to taking a crack at server-side rendering, for example. But, that being said, I'm pretty stoked about this project, and would love some input from you guys!

Thanks for reading!

(Emily)