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