blur effect on menu overlay

Someone knows how to make a menu overlay, that when you click, the background has a blur effect.

Example menu overlay, I put in the overlay class rgba (0,0,0,0,5), but if I put on this class

filter: blur(5px);
-webkit-filter: blur(5px);

only the menu text becomes blur, is there any way for javascript to click on the menu and the background to become blur?

Thank you!