The height read-only property of the SVGRectElement interface describes the vertical size of an SVG rectangle as a SVGAnimatedLength. The length is in user coordinate system units along the y-axis. Its syntax is the same as that for <length>.
It reflects the <rect> element's height presentational attribute. The CSS height property takes precedence over the SVG height presentational attribute, so the value may not reflect the elements actual size. The default value is 0.
const rectangle = document.querySelector("rect");
const rectHeight = rectangle.height;
console.log(rectHeight.baseVal.value); // the `height` value