使用js代码制作网页刮刮乐

 <script type="text/javascript">var canvas = document.getElementById("canvas");var context = canvas.getContext('2d');//画蒙布
 context.beginPath();
 context.fillStyle= 'grey'
 context.fillRect(0,0,400,300);//鼠标按下开刮
 canvas.onmousedown=function(){
 canvas.onmousemove = function(){//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,30,0,Math.PI*2);
 context.fill(); 
 }
 }//鼠标抬起不刮开
 canvas.onmouseup=function(){
 canvas.onmousemove = function(){ 
 }
 } </script>