5 ms·
Advertisers don't just care about clicks. "Impressions" are also an important metric. Much of the jank caused by ads is caused by JavaScript or Flash code that
by cpeterso 9y ago
Advertisers don't just care about clicks. "Impressions" are also an important metric. Much of the jank caused by ads is caused by JavaScript or Flash code that is inefficiently polling the DOM to see if more than 50% of the at is within the browser viewport. This situation should improve with the introduction of the Intersection Observer API which lets the browser call you back when your ad (or other lazily loaded content) is in or near the viewport.