if statement that checks div condition

I have 5 different divs - they are all set to display: none; When the user clicks, the divs become visible (display: block;)

I want to make an if statement that checks if the divs have a value of display: block; and once they do, I want another div to pop-up.

Is this possible? Very new to javascript and I'm trying to be creative and learn. Thanks in advance.