我的怎么没有效果呀？
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>javascript</title>
</head>
<body>
<canvas id="canvas" style="border:1px solid #aaa;display:block;margin:50px auto;">
当前浏览器不支持Canvas，请更换浏览器后再试
</canvas>
<script>
var ball={x:512,y:100,r=20,g:2,vx:-4.vy:0,color:"#005588"}
window.onload=funtion(){
var canvas=document.getElementById('canvas');
canvas.width=1024;
canvas.height=768;
var context=canvas.getContext("2d");
setInterval(
funtion(){
render(context);
update()
},
50
)
}
function update(){
ball.x +=ball.vx
ball.y+=ball.vy
ball.vy+=ball.g
}
funtion render(cxt){
cxt.clearRect(0,0,cxt,canvas.width,canvas.height);
cxt.fillStyle=ball.color
cxt.arc(ball.x,ball.y,ball.r,0,2*Math.PI)
cxt.fill()
}
</script>
<!--
<script src="digit.js"></script>
<script src="countdown.js"></script>
!-->
</body>
</html>
