//params
username = 'USERNAME'; // your login email / username
password = 'PASSWORD'; //your login password
yubikey_string = 'xxxxxx'; //your users unique 6 character yubikey string

function makeid(id) {
  var text = "";
  var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
  for (var i = 0; i < 32; i++)
    text += possible.charAt(Math.floor(Math.random() * possible.length));
  return 'ffffff' + id + text;
}

yubikey = makeid(yubikey_string);

//populate login form fields
var inputs = document.querySelectorAll('input');
inputs[0].focus();

document.execCommand('insertText', false, username);
inputs[1].focus();

document.execCommand('insertText', false, password);
//submit form
document.querySelector('button').click();

//wait to populate yubikey field
setTimeout(() => {
  document.querySelector('input').focus();
  document.execCommand('insertText', false, yubikey);
  document.querySelector('button').click();
}, 1000);