Usage with npm and webpack

[DasElias]

I want to use this library with NPM and webpack, but unfortunately, I don't know how to embed it. At the moment, I have the following JS code:

import 'flexibility';
import $ from 'jquery';

$(function() {
  flexibility(document.documentElement);
})

With this approach, I get the following runtime error: Uncaught ReferenceError: flexibility is not defined.

How is flexibility used correctly with NPM?