The height read-only property of the SVGFEConvolveMatrixElement interface describes the vertical size of an SVG filter primitive as a SVGAnimatedLength.
It reflects the <feConvolveMatrix> element's height filter primitive attribute. The <feConvolveMatrix> filter applies a matrix convolution effect, combining pixels in the input image with neighboring pixels to produce a convolution effect such as blurring, edge detection, sharpening, embossing or beveling. 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 feConvolveMatrix = document.querySelector("feConvolveMatrix");
const verticalSize = feConvolveMatrix.height;
console.log(verticalSize.baseVal.value); // the `height` valueSVGFEConvolveMatrixElement.width<filter> element, SVG filter attribute in SVG