console
for (let i = 1; i <= 4; i++) {
var str = " ";
for (let j = 3; j >= i; j--) {
str +="\xa0\xa0";
}
for (let j = 1; j <= 2 * i - 1; j++) {
str+='*';
}
console.log(str);
}
for (let i = 3; i >= 1; i--) {
var str = " ";
for (let j = 1; j <= 4 - i; j++) {
str +="\xa0\xa0";
}
for (let j = 1; j <= 2 * i - 1; j++) {
str+='*';
}
console.log(str);
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>菱形</title>
<script type="text/javascript"></script>
</head>
<body>
<h2>菱形</h2>
</body>
</html>