The width read-only property of the SVGFECompositeElement interface describes the horizontal size of an SVG filter primitive as a SVGAnimatedLength.
It reflects the <feComposite> element's width filter primitive attribute. The <feComposite> SVG filter primitive combines two input images using a Porter-Duff compositing operation. The attribute is a <length> or a <percentage> relative to the width of the filter region. The default value is 100%. The property value is a length in user coordinate system units.
const feComposite = document.querySelector("feComposite");
const horizontalSize = feComposite.width;
console.log(horizontalSize.baseVal.value); // the `width` valueSVGFECompositeElement.height<blend-mode> data typemix-blend-mode property