<html>
<head>
<script type="text/javascript">
var n=4;//层数
for(var i=1; i<=n; i++)
{
for(var j=1; j<=2*n-1; j++)
{
if(j<=(n-i) || j>=(n+i)){
document.write(" ");//半角空格
}
else
{
document.write("*");
}
}
document.write("<br/>");
}
</script>
</head>
<body>
</body>
</html>
