<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>pick</title>
</head>
<body>
<script type="text/javascript">
function invert(obj) {
for (let k in obj) {
let name = obj[k];
obj[name] = k;
delete obj[k];
}
return obj;
}
const obj = {firstname: "lv", lastname: "meijin"};
console.log(invert(obj));
</script>
</body>
</html>