The ResizeObserverEntry
interface represents the object passed to the ResizeObserver()
constructor's callback function, which allows you to access the new dimensions of the Element
or SVGElement
being observed.
Properties
ResizeObserverEntry.borderBoxSize
Read only- An object containing the new border box size of the observed element when the callback is run.
ResizeObserverEntry.contentBoxSize
Read only- An object containing the new content box size of the observed element when the callback is run.
ResizeObserverEntry.contentRect
Read only- A
DOMRectReadOnly
object containing the new size of the observed element when the callback is run. Note that this is better supported than the above two properties, but it is left over from an earlier implementation of the Resize Observer API, is still included in the spec for web compat reasons, and may be deprecated in future versions. ResizeObserverEntry.target
Read only- A reference to the
Element
orSVGElement
being observed.
Note: The content box is the box in which content can be placed, meaning the border box minus the padding and border width. The border box encompasses the content, padding, and border. See The box model for further explanation.
Methods
None.
Examples
The following snippet is taken from the resize-observer-text.html (see source) example. This uses a simple feature detection test to see if the browser supports the newer contentBoxSize
property — if so, it uses that to get the sizing data it needs. If not, it uses the older contentRect
property.
const resizeObserver = new ResizeObserver(entries => { for (let entry of entries) { if(entry.contentBoxSize) { h1Elem.style.fontSize = Math.max(1.5, entry.contentBoxSize.inlineSize/200) + 'rem'; pElem.style.fontSize = Math.max(1, entry.contentBoxSize.inlineSize/600) + 'rem'; } else { h1Elem.style.fontSize = Math.max(1.5, entry.contentRect.width/200) + 'rem'; pElem.style.fontSize = Math.max(1, entry.contentRect.width/600) + 'rem'; } } }); resizeObserver.observe(divElem);
Specifications
Specification | Status | Comment |
---|---|---|
Resize Observer The definition of 'ResizeObserverEntry' in that specification. |
Editor's Draft | Initial definition. |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
ResizeObserverEntry | Chrome Full support 64 | Edge Full support 79 | Firefox Full support 69 | IE No support No | Opera Full support Yes | Safari No support No | WebView Android Full support 64 | Chrome Android Full support 64 | Firefox Android No support No | Opera Android Full support Yes | Safari iOS No support No | Samsung Internet Android Full support 9.0 |
borderBoxSize | Chrome No support No | Edge No support No | Firefox Full support 69 | IE No support No | Opera No support No | Safari No support No | WebView Android No support No | Chrome Android No support No | Firefox Android No support No | Opera Android No support No | Safari iOS No support No | Samsung Internet Android No support No |
contentBoxSize | Chrome No support No | Edge No support No | Firefox Full support 69 | IE No support No | Opera No support No | Safari No support No | WebView Android No support No | Chrome Android No support No | Firefox Android No support No | Opera Android No support No | Safari iOS No support No | Samsung Internet Android No support No |
contentRect | Chrome Full support 64 | Edge Full support 79 | Firefox Full support 69 | IE No support No | Opera Full support Yes | Safari No support No | WebView Android Full support 64 | Chrome Android Full support 64 | Firefox Android No support No | Opera Android Full support Yes | Safari iOS No support No | Samsung Internet Android Full support 9.0 |
target | Chrome Full support 64 | Edge Full support 79 | Firefox Full support 69 | IE No support No | Opera Full support Yes | Safari No support No | WebView Android Full support 64 | Chrome Android Full support 64 | Firefox Android No support No | Opera Android Full support Yes | Safari iOS No support No | Samsung Internet Android Full support 9.0 |
Legend
- Full support
- Full support
- No support
- No support
- Experimental. Expect behavior to change in the future.
- Experimental. Expect behavior to change in the future.