LayoutShiftAttribution

The LayoutShiftAttribution interface of the Layout Instability API provides debugging information about elements which have shifted.

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

Properties

LayoutShiftAttribution.NodeRead only

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

LayoutShiftAttribution.previousRectRead only

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

LayoutShiftAttribution.currentRectRead only

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

Methods

LayoutShiftAttribution.toJSON()

Returns a JSON representation of the LayoutShiftAttribution object.

Examples

The following example finds the element that is causing the largest layout shift, and prints that node to the console. For more detail on this see Debug Web Vitals in the field.

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

Specifications

Specification
Layout Instability
# sec-layout-shift-attribution

Browser compatibility

BCD tables only load in the browser

See also