You can still track users just fine without Flash - the VPAID spec calls for allowing cross-domain &quot;Friendly&quot; scripting access, which is horrible for users.[1]<p>The only problem with Javascript adoption was the availability of Javascript based ads and support for this VPAID style tracking.<p>[1] <a href="http:&#x2F;&#x2F;www.iab.com&#x2F;wp-content&#x2F;uploads&#x2F;2015&#x2F;06&#x2F;VPAID_2_0_Final_04-10-2012.pdf" rel="nofollow">http:&#x2F;&#x2F;www.iab.com&#x2F;wp-content&#x2F;uploads&#x2F;2015&#x2F;06&#x2F;VPAID_2_0_Fina...</a> - VPAID 2.0 spec, section 8.1.3: &quot;The VPAID ad unit is rendered within a friendly IFRAME (FIF) and can access the DOM of the page in which the player is rendered.&quot;