ant-design/components/affix/index.en-US.md

category	type	title
Components	Navigation	Affix

Make an element stick to viewport.

When To Use

When user browses a long web page, some content need to stick to the viewport. This is common for menus and actions.

Please note that Affix should not cover other content on the page, especially when the size of the viewport is small.

API

Property	Description	Type	Default
offsetBottom	Pixels to offset from bottom when calculating position of scroll	number	-
offsetTop	Pixels to offset from top when calculating position of scroll	number	0
target	specifies the scrollable area dom node	() => HTMLElement	() => window
onChange	Callback for when affix state is changed	Function(affixed)	-

Note: Children of Affix can not be position: absolute, but you can set Affix as position: absolute:

<Affix style={{ position: 'absolute', top: y, left: x }}>
  ...
</Affix>

FAQ

Affix bind container with target, sometime move out of container.

We don't listen window scroll for performance consideration. You can add listener if you still want: https://codesandbox.io/s/2xyj5zr85p

Related issue：#3938 #5642 #16120