获取鼠标坐标 var x = event.clientX; var y = event.clientY; //destination-out 显示原来的不在后来区域的部分 context.globalCompositeOperation = "destination-out"; context.beginPath(); context.arc(x-200,y,30,Math.PI*2); context.fill(); } } //鼠标抬起不刮开 canvas.onmouseup=function(){ canvas.onmousemove = function(){ } }