how could I find out which series was clicked on in the legend?

[Joe Hudson]

Hi and thanks in advance for any help.  Could you please help me understand
what to do here?

const element = document.getElementById(...);
const chart = echarts.init(element);
element.addEventListener('contextmenu', (ev) => {
  const xPos = ev.offsetX;
  const yPos = ev.offsetY;
  // how can I take the x and y position to see if it represents a series
label?
});

Thanks so much for your help!

Joe