The height read-only property of the SVGFEDisplacementMapElement interface describes the vertical size of an SVG filter primitive as a SVGAnimatedLength.
It reflects the <feDisplacementMap> element's height filter primitive attribute. The attribute is a <length> or a <percentage> relative to the height of the filter region. The default value is 100%. The property value is a length in user coordinate system units.
const feDisplacementMap = document.querySelector("feDisplacementMap");
const verticalSize = feDisplacementMap.height;
console.log(verticalSize.baseVal.value); // the `height` valueSVGFEDisplacementMapElement.widthSVGFEImageElement API and <feImage> elementSVGFETurbulenceElement API and <feTurbulence> element<blend-mode> data typemix-blend-mode property