javascript image cropper or javascript image filters depending on what I'm looking to do.

I would look for example code. I prefer vanilla javascript over libraries as they usually come with a lot of features I don't need. I might still end up using a library though, if it's lightweight.

( Might be worth writing some blog posts for different JS frameworks including plain old JS, with simplified ways of doing what your library does. Then when somebody wants extra functionality they know where to find you. )