Angular.io (probably node.js) way to create/import javascript files as modules

I would like first of all to point out that my knowledge in this field is pretty limited at this moment and the purpose of this question is to start moving the direction where the things become clear and useful.

For the purpose of this question, the following Typist plugin has been selected, where the author suggests to import the code using the good old <script> tag inside the index.html. But for example in angular/react and other component based frameworks it has become very common to import modules into a component and directly implement them inside.

Can you please define/suggest a route of basic logic/information I should learn in order to be able consciously declare and manage such plugins as modules, import them into components and launch directly from the last ones.

via Adrian Sol