How are such widgets created?

Question

JavaScript

For example, various calendars, datepickers, etc., when by clicking on an icon, an input field... a calendar or some other element appears in the same place. Is the element created and positioned relative to the element that fires the event, or is the element immediately in the right place and just hidden? And how to do it right, if you implement it yourself?

Answer 1

You can position in different ways according to the coordinates of the mouse, you can click on the element, or maybe it was hidden there beforehand.
Here is an example https://jsfiddle.net/65Lxxa2n/1/