Run npm install in the project directory, to install all the gulp dependencies
Run gulp watch to start task manager. Gulp should take care of mostly everything.
NPM only manages the Gulp Dependencies. It is not used to manage the front-end dependencies.
English version https://docs.google.com/document/d/1jeCYVUz_a6tiUd7WFjl0taTwOOdUMaNL7C6VXzqeHxI/edit#heading=h.flj2izcfrwcu
French Version https://docs.google.com/document/d/1URq4NUUjun8FCPZjdIUMG0LePPeo-kX77GmB-tMsYIc/edit#heading=h.gjdgxs