platform/video.videojs/dist/video.es.js
function getPointerPosition(el, event) {
  var position = {};
  var box = findPosition(el);
  var boxW = el.offsetWidth;
  var boxH = el.offsetHeight;

  var boxY = box.top;
  var boxX = box.left;
  var pageY = event.pageY;
  var pageX = event.pageX;

  if (event.changedTouches) {
    pageX = event.changedTouches[0].pageX;
    pageY = event.changedTouches[0].pageY;
  }

  position.y = Math.max(0, Math.min(1, (boxY - pageY + boxH) / boxH));
  position.x = Math.max(0, Math.min(1, (pageX - boxX) / boxW));

  return position;
}
function getPointerPosition(el, event) {
  var position = {};
  var box = findPosition(el);
  var boxW = el.offsetWidth;
  var boxH = el.offsetHeight;

  var boxY = box.top;
  var boxX = box.left;
  var pageY = event.pageY;
  var pageX = event.pageX;

  if (event.changedTouches) {
    pageX = event.changedTouches[0].pageX;
    pageY = event.changedTouches[0].pageY;
  }

  position.y = Math.max(0, Math.min(1, (boxY - pageY + boxH) / boxH));
  position.x = Math.max(0, Math.min(1, (pageX - boxX) / boxW));

  return position;
}
x and y coordinates for a dom element or mouse pointer

@typedef {Object} Dom~Coordinates

@property {number} x
x coordinate in pixels

@property {number} y
y coordinate in pixels
 
Get pointer position in element
Returns an object with x and y coordinates.
The base on the coordinates are the bottom left of the element.

@param {Element} el
Element on which to get the pointer position on

@param {EventTarget~Event} event
Event object

@return {Dom~Coordinates}
A Coordinates object corresponding to the mouse position.