Custom Fields in Auth0

example.html

<!-- Other HTML above -->
<script src="https://cdn.auth0.com/js/lock/11.27/lock.min.js"></script>
<script>
  var lock = new Auth0Lock(config.clientID, config.auth0Domain, {
    auth: {
      redirectUrl: config.callbackURL,
      responseType: (config.internalOptions || {}).response_type ||
        (config.callbackOnLocationHash ? 'token' : 'code'),
      params: config.internalOptions
    },
    
    ... (etc., other options),
    
    // The part you care about here
    additionalSignUpFields: [{
      name: "nickname",
      storage: "root",
      placeholder: "enter a unique username",
      icon: "https://res.cloudinary.com/orpheus-studios/image/upload/c_scale,h_12/v1617793473/baseline_person_gray_24dp_iua7nk.png",
      validator: function(nickname) {
        return {
          valid: nickname.length >= 4 && nickname.length <= 15,
          hint: "Must be between 4 and 15 characters"
        };
      }
    }]
  });
</script>