code: function updateTimeProgression(curve, x, y) {
          var percentX = Math.round(100 * x / WIDTH_MAIN),
              percentY = Math.round(100 * ((HEIGHT_MAIN - y) / HEIGHT_MAIN));
  
          // Constrain horizontal percentage to [0, 100] range
          percentX = Math.min(Math.max(0, percentX), 100);
  
          curve.parentNode.setAttribute("data-time", percentX);
          curve.parentNode.setAttribute("data-progression", percentY);
      }
docs: Update Time (x-axis) and Progression (y-axis) data for mouse position
  
  @param {Element} canvas <canvas> element
  @param {number} x Horizontal position
  @param {number} y Vertical position