This project was built by following Wes Bos's JavaScript 30 course. It is an interactive drawing app using the HTML5 Canvas API, where colours and brush sizes change dynamically as you draw.
ctx.strokeStyle = `hsl(${hue}, 100%, 50%)`;
ctx.beginPath();
ctx.moveTo(lastX, lastY);
ctx.lineTo(e.offsetX, e.offsetY);
ctx.stroke();