How to execute code when object is not visible?

Question

PHP

Hello. How on jQuery it is possible to execute for example alert(1);
when #navbar disappears from the field of view during scrolling, and vice versa when alert(0);
It will be visible initially.
I will be very grateful

Answer 1

open the env file(s) and quote any parameters with spaces.

Answer 2

if scroll height > navbar height show alert(1)