get_userdata by username

I am currently working with the REST API and have the need to get_userdata() but instead of the user_id I have the username I also have their email if that helps.

Question: Is this possible within the core functionality of WordPress? If not is there a round about way to get user info via username and then get the user_id from that to do the get_userdata call?

get_userdata() function is an alias of get_user_by('ID') function. Use this code:

$username="your user name";
$user = get_user_by('login', $username);

It will return WP_User object on success, or false on failure. See Codex.

REST API: http://example.com/wp-json/wp/v2/users/<id>