Earlier quoted context omitted.
> Multiple versions [...] almost always a bad idea If so, different major versions of the same dep should be considered different libraries, for the sake of flattening. Consider lodash for example.
That can cause some serious problems in at least some portion of times. I've dealt with the subtle errors that have been caused by this problem in c++, and don't really know javascript libraries that well so I can't give a more concrete example. But imagine that there are the following libraries: * LA: handles linear algebra and defines a matrix object. * A: reads in a csv file and generates a matrix object using LA…
* Figure out early on (before 1.0) what your base interface will be.
For example, for a promise library, that would be `then` as specified by Promises/A+
* Check if the argument is an instance of the exact same version.
This works well enough if you use `instanceof`, since classes defined in a different copy of the module will have their own class value - a different unique object.
* If instanceof returns true, use the fast path code (no conversion)
* Otherwise, perform a conversion (e.g. "thenable" assimilation) that
only relies on the base interface