Full stack MEAN Invoice app with custom form elements

Hi, everyone. I would like to present this simple invoice app as my second solution on this platform. It features custom datepicker and multiselect form elements and uses Node.js + Express.js for a backend. If you happen to see an empty page, just let the backend to wake up and you should see the data in a few seconds. You might also want to go through the README file as this project uses the latest stuff that is not yet available in every browser. If you have any suggestion or question, don't hesitate to ask, thanks.