The width read-only property of the SVGFEBlendElement interface describes the horizontal size of an SVG filter primitive as a SVGAnimatedLength.
It reflects the <feBlend> element's width filter primitive attribute. 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.
The <feBlend> SVG filter blends two input images together using commonly used imaging software blending modes.
const feBlend = document.querySelector("feBlend");
const horizontalSize = feBlend.width;
console.log(horizontalSize.baseVal.value); // the `width` valueSVGFEBlendElement.height<blend-mode> data typemix-blend-mode property