The height read-only property of the SVGFEDropShadowElement interface describes the vertical size of an SVG filter primitive as a SVGAnimatedLength.
It reflects the 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 feDropShadow = document.querySelector("feDropShadow");
const verticalSize = feDropShadow.height;
console.log(verticalSize.baseVal.value); // the `height` valueSVGFEDropShadowElement.widthdrop-shadow() functionbox-shadow propertytext-shadow property<blend-mode> data typemix-blend-mode property