js for循环输出三角形
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<script type="text/javascript">
function sanjiao(){
for(var i=0;i<9;i++){
for(var j=0;j<9-i-1;j++){
document.write(" ")
}
for(var k=0;k<2i+1;k++){
document.write("")
}
document.write("
")
}
}
sanjiao();
