<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title>打印倒正三角形</title>
</head>
<style type="text/css">
div{text-align: center;line-height: 25px;}
</style>
<body>
<div>
<script >
document.write("<h2>打印倒三角</h2>")
var a=prompt("请输入一个数")
for(var i=a;i>0;i--){
for(var j=0;j<i;j++){
document.write("* ")
}
document.write("<br/>")
}
for(var k=1;k<=a-1;k++){
for(var h=0;h<k+1;h++){
document.write("* ")
}
document.write("<br/>")
}
</script>
</div>
</body>
</html>