<div style="position:absolute;bottom:20%;left:5%;width:90%;overflow:scroll;">

<canvas id="myCanvas" width="1320px" height="400px" style="border:1px solid #d3d3d3;background:lightblue;"></canvas>

</div>

window.onload = function(){

  var can = document.getElementById('myCanvas');

  var pro = can.innerHTML.substring(0,can.innerHTML.length-1);

  console.log(pro);

  var cxt = can.getContext('2d'); 

}