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LayoutShiftAttribution

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The LayoutShiftAttribution interface provides debugging information about elements which have shifted.

Instances of LayoutShiftAttribution are returned in an array by calling LayoutShift.sources.

Instance properties

LayoutShiftAttribution.node Read only Experimental

Returns the element that has shifted (null if it has been removed).

LayoutShiftAttribution.previousRect Read only Experimental

Returns a DOMRectReadOnly object representing the position of the element before the shift.

LayoutShiftAttribution.currentRect Read only Experimental

Returns a DOMRectReadOnly object representing the position of the element after the shift.

Instance methods

LayoutShiftAttribution.toJSON() Experimental

Returns a JSON representation of the LayoutShiftAttribution object.

Examples

The following example finds the element with the highest layout shift score, and returns the element in that entry with the largest size prior to the shift (previousRect). For more detail on this see Debug Web Vitals in the field.

js

function getCLSDebugTarget(entries) {
  const largestEntry = entries.reduce((a, b) =>
    a && a.value > b.value ? a : b,
  );
  if (largestEntry?.sources?.length) {
    const largestSource = largestEntry.sources.reduce((a, b) => {
      const area = (el) => el.previousRect.width * el.previousRect.height;
      return a.node && area(a) > area(b) ? a : b;
    });
    if (largestSource) {
      return largestSource.node;
    }
  }
}

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
LayoutShiftAttribution 84 84 No No 70 No 84 84 No 60 No 14.0
currentRect 84 84 No No 70 No 84 84 No 60 No 14.0
node 84 84 No No 70 No 84 84 No 60 No 14.0
previousRect 84 84 No No 70 No 84 84 No 60 No 14.0
toJSON 84 84 No No 70 No 84 84 No 60 No 14.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/LayoutShiftAttribution