draw.js first

$(document).ready(function() {
  const canvas = document.getElementById("mycanvas");
  console.log(canvas);
  let ctx = canvas.getContext("2d");
  // get context to draw on canvas
  let DIMENSION = 25;
  let WIDTH = canvas.width;
  let HEIGHT = canvas.height;

  ctx.strokeStyle = 'rgba(0,0,0,0.1)';
  for (let i = 0; i < DIMENSION; ++i) {
    x = Math.floor(i * WIDTH / DIMENSION);
    ctx.beginPath();
    ctx.moveTo(x, 0);
    ctx.lineTo(x, HEIGHT);
    ctx.stroke();

    y = Math.floor(i * HEIGHT / DIMENSION);
    ctx.beginPath();
    ctx.moveTo(0, y);
    ctx.lineTo(WIDTH, y);
    ctx.stroke();
  }
});