How to implement applying a property to only one element of the list?

Question

JavaScript

There are menu items in the form of a list li. I want that when I click on an element, a certain background is applied to it. When clicking on another element, the background from the previous one returned to the original one, and was applied to the active one. I've been struggling for the third hour, as soon as I haven't tried it, it doesn't work, please tell me.

Answer 1

In the simplest version, like this - jsfiddle.net/6xesudr6