JSFiddle - React, Tailwind, and code Playground

HTML

<svg>
    <defs>
        <marker id="marker" overflow="visible">
            <circle r="10"/>
        </marker>
    </defs>
    <path id="r" d="M20,20h100v100h-100z" marker-start="url(#marker)" marker-mid="url(#marker)"/>
</svg>

JavaScript

function rectToString(rect) {
  return rect.left + "," + rect.top + "," + rect.width + "," + rect.height;
};

var p = document.createElement("p");
p.textContent = "bbox: " + rectToString(document.getElementById("r").getBoundingClientRect());

document.body.appendChild(p);