<svg viewBox="0 0 20 10" xmlns="http://www.w3.org/2000/svg">
  <!--
  The circle will always intercept the mouse event.
  To change the color of the rect underneath you have
  to click outside the circle
  -->
  <rect x="0" y="0" height="10" width="10" fill="black" />
  <circle cx="5" cy="5" r="4" fill="white" pointer-events="visiblePainted" />

  <!--
  The circle below will never catch a mouse event.
  The rect underneath will change color whether you
  are clicking on the circle or the rect itself
  -->
  <rect x="10" y="0" height="10" width="10" fill="black" />
  <circle cx="15" cy="5" r="4" fill="white" pointer-events="none" />
</svg>

window.addEventListener("mouseup", (e) => {
  // Let's pick a random color between #000000 and #FFFFFF
  const color = Math.round(Math.random() * 0xffffff);

  // Let's format the color to fit CSS requirements
  const fill = `#${color.toString(16).padStart(6, "0")}`;

  // Let's apply our color in the
  // element we actually clicked on
  e.target.style.fill = fill;
});