Chromium Blog: Scroll anchoring for web developers

Chromium Blog

News and developments from the open source browser project

Scroll anchoring for web developers

Tuesday, April 11, 2017

One of the strengths of the web is progressive loading, which means that there is no install step and users can start consuming content almost immediately while the site keeps loading. But progressive loading can also result in annoyances, such as an unexpected page jump when offscreen content loads and pushes down what’s currently on the screen. This can be even worse on mobile devices, since smaller screens mean more content is offscreen and page jumps are more likely.

Since its early days, Chrome has taken a stand against bad or abusive content. For instance, Safe Browsing warns users before they visit malicious websites, and visual indicators on tabs allow our users to quickly track down the source of unexpected noise. Similar to other features designed to protect our users from bad experiences, starting in version 56 Chrome prevents these unexpected page jumps with a new feature called scroll anchoring. This feature works by locking the scroll position on an on-screen element to keep our users in the same spot even as offscreen content continues to load.

Side by side comparison of a web page with scroll anchoring disabled (left) and enabled (right).

Due to the expressiveness of the web, there might be some content for which scroll anchoring is either unwanted or misbehaving. For this reason, this feature ships alongside the ”overflow-anchor” CSS property to override the functionality. To further minimize potential issues, scroll anchoring is disabled on complex interactive layouts via suppression triggers, and on back/forward navigations to allow for scroll restoration.

Today, scroll anchoring is preventing about three page jumps per page-view, but with your help it could be even better. Get involved by participating in the scroll anchoring Web Platform Incubator Community Group, submitting feedback via g.co/reportbadreflow, and designing your websites or services with a no-reflow mindset.