这个为什么执行到9就下不去了
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gkb"/>
</head>
<body>
<script type="text/javascript">
var a =10;
function x(){
a =a -1;
document.write(a);
setTimeout(x,1000)
}
setTimeout(x,1000);
</script>
</body>
</html>
