Not all ad blockers remove elements from web pages, and if they acted that predictably you could detect the ad blocker by detecting whether an expected element is hidden.
I have not looked through an ad blocker’s code, but I don’t believe it is that simple.
Looking at this blogpost for a wordpress blocking plugin, it basically is just adding a bunch of css classes commonly used by ads to a div and some workarounds to support ad blockers that work by blocking files.
Not all ad blockers remove elements from web pages, and if they acted that predictably you could detect the ad blocker by detecting whether an expected element is hidden.
I have not looked through an ad blocker’s code, but I don’t believe it is that simple.
Looking at this blogpost for a wordpress blocking plugin, it basically is just adding a bunch of css classes commonly used by ads to a div and some workarounds to support ad blockers that work by blocking files.