可选链操作符
<!DOCTYPE html>
<html lang="en">
<head>
<Meta charset="UTF-8">
<title>es11-可选链操作符</title>
</head>
<body>
<script>
function connect(config) {
//const host = config && config.db && config.db.host;
//?.可选链操作符
const host = config?.db?.host;
console.log(host);
}
connect({
db:{
host:'127.0.0.1'
}
})
</script>
</body>
</html>