I don't know what to call these, so I'm calling them "reverse pop-ups" (or maybe "reverse pop-unders.") This is a thing where, when you click a link:

• the destination URL for the link opens in a new tab/window (whether you middle-clicked or not)
• the tab you were currently viewing navigates to an ad page
• if you didn't middle-click, then the new tab with the destination URL also steals focus.

If the new tab manages to steal focus, then the original tab gets to navigate to an ad page while hidden from view, leaving the ad to be discovered only when you close the new tab. This gives the effect of a pop-under, but browser pop-up blocking logic can't do anything about it, since in this case the "technically a pop-up window" window contains the thing the user wants to see, while the window playing the role of a pop-under is the already-existing original tab.

The only way to avoid this is to avoid the onclick handler firing (e.g. by right-clicking the link and selecting "Open in New Tab.") Disabling Javascript usually doesn't work, as the links are usually pulled in via an XHR in the first place. It might be even harder in some cases, because the links might have no real href targets (or other DOM-accessible data attributes containing the target URL), only pure Javascript state the onclick handler uses to open the right URL for the link.

I apologize in advance for the particular examples; I've only ever seen this effect occur on very scummy websites. (I'm using a throwaway account to post a bug report; that's pretty novel!)

• An easy-to-access example occurs on this directory of "escort" services. Just click any listing.

• Another example occurs on this Craigslist knock-off website. I think it only triggers once you've registered logged in, navigated into one of the "personals" sections, and then clicked a listing. (Otherwise, you don't get an ad, just redirected to a Login page.)

Is there any way to block this behavior generally, rather than with site-specific shimming? I can't think of a single case where it would be warranted by default to perform this sequence of steps (open new tab, switch focus, navigate original tab) on click.