> Technical curiosity: how site owners are able to detect blockers Let's take a simple rule from EasyList: > /snowplow.js This blocks the loading of any URL

> Technical curiosity: how site owners are able to detect blockers Let's take a simple rule from EasyList: > /snowplow.js This blocks the loading of any URL ending in snowplow.js. To see if a visitor to my website is using an ad blocker with EasyList, I can set a global variable `window.usingAdBlocker = true;` in my main content and then later change it in a scriptcalled snowplow.js that I include (`window.usingAdBlocker = false;`). So with a fresh Chrome install, the page loads and then the script sets the variable to false. However, with an ad blocker, the script never loads and the variable remains true. > why blockers are not able to bypass detection? Adblockers have developed rules to block this detection mechanism. It is a cat and mouse game. For example, there's a library called 'jQuery Adblock'. So the AakList (Anti-Adblock Killer) has a rule to block scripts called `/jquery.adblock.js` It is a cat and mouse game.