Get XY coordinates as percentages

getxypercent.js

// 1. Load an image in a new tab
// 2. Open JS console. Leave it open
// 3. Paste this
var s = document.createElement('script');
s.setAttribute('src','https://code.jquery.com/jquery-2.1.4.min.js');
document.head.appendChild(s);

// 4. Then paste this
var oldx = 0, oldy = 0;

var newImg = $('img').attr('src');

$('img').detach();

$('body').append('<img src="' + newImg + '" style="margin:0; height:100vh; width:auto">');

$('img').off( "click" ).click(function(e) {
  var offset = $(this).offset();
  var x = Math.floor((e.pageX - offset.left) / $(this).width() * 10000)/100;
  var y = Math.floor((e.pageY - offset.top) / $(this).height() * 10000)/100;

  console.log(x, y, x - oldx, y - oldy);
  oldx = x; oldy = y;
});

// 5. Click on the points you're interested. You'll get x,y coordinates in percentage of the image
// and dx and dy from the previous clicked point.

It works perfect. Thank you.