Quiero hacer un dibujo de lienzo pero este código no funciona en el navegador móvil

 const canvas = document.getElementById("draw"); canvas.width = window.innerWidth - 60; canvas.height = 400; let context = canvas.getContext("2d"); context.fillStyle = "white"; context.fillRect(0, 0, canvas.width, canvas.height); let draw_color = "black"; let draw_width = "2"; let is_drawing = false; canvas.addEventListener("touchstart", start, false); canvas.addEventListener("touchmove", draw, false); canvas.addEventListener("mousedown", start, false); canvas.addEventListener("mousemove", draw, false); canvas.addEventListener("touchend", stop, false); canvas.addEventListener("mouseup", stop, false); canvas.addEventListener("mouseout", stop, false); function start(event) { is_drawing = true; context.beginPath(); context.moveTo(event.clientX - canvas.offsetLeft, event.clientY - canvas.offsetTop); event.preventDefault(); } function draw(event) { if (is_drawing) { context.lineTo(event.clientX - canvas.offsetLeft, event.clientY - canvas.offsetTop); context.strokeStyle = draw_color; context.lineWidth = draw_width; context.lineCap = "round"; context.lineJoin = "round"; context.stroke(); } event.preventDefault(); } function stop(event) { if (is_drawing) { context.stroke(); context.closePath(); is_drawing = false; } event.preventDefault(); }