Detection
Some webmasters have used JavaScript to detect the effects of the popular Adblock filters. This is done by generating a honeypot-like URL, verifying its delivery, and DOM verification after the web page is rendered by the web browser, to ensure the expected advertising elements are present. Detection is simplified since the extension is not yet capable of replacing content; Loopback proxies provide this additional functionality.
These methods do not detect the presence of the Adblock extension directly, only the effects of the filters. They are vulnerable to continued filter updates, and whitelist-filtering web scripts with extensions such as NoScript.
An attempt was made to detect the plug-in itself, but that detection method was rendered unusable by the 0.7.5.2 update of Adblock Plus.
Google Chrome had a defect in Content Security Policy that allowed to detect of any installed extension, including Adblock Plus for Google Chrome. The solution of this was possible only in Google Chrome 18, and requires each developer to make some changes in their extensions. Adblock Plus for Google Chrome fixed this in version 1.3.
Read more about this topic: Adblock