IntersectionObserver interface's read-only
rootMargin property is a string with syntax similar to
that of the CSS
margin property. Each side of the rectangle represented
rootMargin is added to the corresponding side in the
root element's bounding box
before the intersection test is performed. This lets you, for example, adjust the bounds
outward so that the target element is considered 100% visible even if a certain number
of pixels worth of width or height is clipped away, or treat the target as partially
hidden if an edge is too close to the edge of the root's bounding box.
See how intersections are calculated for a more in-depth look at the root margin and how it works with the root's bounding box.
A string, formatted similarly to the CSS
margin property's value, which
contains offsets for one or more sides of the root's bounding box. These offsets are
added to the corresponding values in the root's bounding box before the intersection
between the resulting rectangle and the target element's bounds.
The string returned by this property may not match the one specified when the
IntersectionObserver was instantiated. The browser is permitted to alter
rootMargin isn't specified when the object was instantiated, it
defaults to the string
"0px 0px 0px 0px", meaning that the intersection
will be computed between the root element's unmodified bounds rectangle and the target's
bounds. How intersections are calculated
describes how the
rootMargin is used in more detail.
|Intersection Observer |
BCD tables only load in the browser