As a user of the web, you are probably familiar with the problem that scroll anchoring solves. You browse to a long page on a slow connection and begin to scroll to read the content; while you are busy reading, the part of the page you are looking at suddenly jumps. This has happened because large images or some other elements have just loaded further up in the content.
Scroll anchoring is a browser feature that aims to solve this problem of content jumping, which happens if content loads in after the user has already scrolled to a new part of the document.
Scroll anchoring adjusts the scroll position to compensate for the changes outside of the viewport. This means that the point in the document the user is looking at remains in the viewport, which may mean their scroll position actually changes in terms of how far they have moved through the document.
You don't! The feature is enabled by default in supporting browsers. In most cases anchored scrolling is exactly what you want — content jumping is a poor experience for anyone.
If your page is not behaving well with scroll anchoring enabled, it is probably because some
scroll
event listener is not handling well the extra scrolling to compensate for the anchor node movement.
You can check whether disabling scroll anchoring fixes the issue in Firefox by changing
layout.css.scroll-anchoring.enabled
to
false
in
about:config
.
If it does, you can check what node is Firefox using as the anchor using the
layout.css.scroll-anchoring.highlight
switch. That will show a purple overlay on top of the anchor node.
If one node doesn't seem appropriate to be an anchor, you can exclude it using
overflow-anchor
, as described below.
The specification provides a new property,
overflow-anchor
, which can be used to disable scroll anchoring on all or part of the document. It's essentially a way to opt out of the new behavior.
The only possible values are
auto
or
none
:
auto
is the initial value; as long as the user has a supported browser the scroll anchoring behavior will happen, and they should see fewer content jumps.
none
means that you have explicitly opted the document, or part of the document, out of scroll anchoring.
To opt out the entire document, you can set it on the
<body>
元素：
body {
overflow-anchor: none;
}
To opt out a certain part of the document use
overflow-anchor: none
on its container element:
.container {
overflow-anchor: none;
}
注意
: The specification details that once scroll anchoring has been opted out of, you cannot opt back into it from a child element. For example, if you opt out for the entire document, you will not be able to set
overflow-anchor: auto
elsewhere in the document to turn it back on for a subsection.
The specification also details some suppression triggers , which will disable scroll anchoring in places where it might be problematic. If any of the triggers happen on the anchor node, or an ancestor of it, anchoring is suppressed.
These suppression triggers are changes to the computed value of any of the following properties:
Additionally,
position
changes anywhere inside the scrolling box also disable scroll anchoring.
在
bug 1584285
the
layout.css.scroll-anchoring.suppressions.enabled
flag was added to Firefox Nightly in order to allow the disabling of these triggers.
If you need to test whether scroll anchoring is available in a browser, use
Feature Queries
to test support for the
overflow-anchor
特性。
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
overflow-anchor
|
Chrome 完整支持 56 | Edge 完整支持 79 | Firefox 完整支持 66 | IE 不支持 No | Opera 完整支持 43 | Safari 不支持 No | WebView Android 完整支持 56 | Chrome Android 完整支持 56 | Firefox Android 不支持 No | Opera Android 完整支持 43 | Safari iOS 不支持 No | Samsung Internet Android 完整支持 6.0 |
完整支持
不支持