code: function drawGradient(ctx, x1, y1, x2, y2, colorStops, x, y, width, height) {
    var grad;
  
    ctx.save();
    grad = ctx.createLinearGradient(x1, y1, x2, y2);
  
    colorStops.forEach(function (colorStop) {
      grad.addColorStop(colorStop.position, colorStop.color);
    });
  
    ctx.fillStyle = grad;
    ctx.fillRect(x, y, width, height);
    ctx.restore();
  }
docs: Draw a linear gradient
  
  @param {CanvasContext} ctx
  @param {Number} x1 gradient start-x coordinate
  @param {Number} y1 gradient start-y coordinate
  @param {Number} x2 gradient end-x coordinate
  @param {Number} y2 gradient end-y coordinate
  @param {Array} colorStops Array of {(String)color, (Number)position} values
  @param {Number} x x-coordinate to begin fill
  @param {Number} y y-coordinate to begin fill
  @param {Number} width how wide to fill
  @param {Number} height how tall to fill