#myCanvas
贝塞尔曲线
20,100,200,100,200,20|20,100,200,200,200,20|20,100,200,300,200,20|20,100,200,500,200,20|20,100,200,0,200,20|20,100,200,-100,200,20|20,100,200,-300,200,20|20,100,200,-500,200,20
400
ctx.beginPath();
ctx.moveTo(20,20);
ctx.bezierCurveTo(#val);
ctx.stroke();