Inline date edit with nojQuery

Inline Datepicker with vanilla JavaScript

I do write a lot of front-end code, despite being born to be a back-end guy. Long story short - we do have many inline editing features, especially elements like dates, which are pretty painful. HTML5 Introduced input type=date , which is good enough to cover most of the cases, and we no longer need ugly and slow .datepicker() component from jQuery od 3rd party suppliers.

So if you do have edit you can use <input type="date" value="yyyy-mm-dd"> field, and a nice calendar will pop up. But we are looking for inline solution.