detect click position code example

Example 1: js get mouseclick

function printMousePos(event) {
  document.body.textContent =
    "clientX: " + event.clientX +
    " - clientY: " + event.clientY;
}

document.addEventListener("click", printMousePos);

Example 2: javascript onclick select coordinates

var x;
var y;
if (e.pageX || e.pageY) { 
  x = e.pageX;
  y = e.pageY;
}
else { 
  x = e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft; 
  y = e.clientY + document.body.scrollTop + document.documentElement.scrollTop; 
} 
x -= gCanvasElement.offsetLeft;
y -= gCanvasElement.offsetTop;