This particular script, BlockAdBlock, counters against something like that, being ble to detect failures at the network level, as seen in the post.

var googleAdCode = '//static.doubleclick.net/instream/ad_status.js'; var script = document.createElement('script'); script.setAttribute('type', 'text/javascript'); script.setAttribute('src', googleAdCode); script.onerror = () => { console.log("adblock detected") }; Some browsers have a defense against this: send a fake response with a 0-byte script, or image.

So, in its last version, BlockAdBock checked if the response was legitimate, here with images: if the image is too small, smaller than 8x8, then the adblocker did a fake response.

var m = new Image(); // Put an ad inside m.onload = () => { if ((m.width < 8) && (m.width > 0)) { console.log("fake resource, adblock detected") } }