How to implement such a color template add-on?

Question

JavaScript

Hello.
Maybe someone did or met on themeforest'e in some templates there are color settings and all sorts of little things, somewhere in some corner of the gear and when pressed, the color palette leaves and depending on the choice of color in the palette, for example, the main color on the site changes. or main font.
How to implement this?

Answer 1

I sketched a simple example for you https://codepen.io/aliencash/pen/jLWroP?editors=1100#0

Answer 2

usefulscript.ru/select_background_color.php