firebase-phone-auth-sample.js

function getUiConfig() {
  return {
    'callbacks': {
      // Called when the user has been successfully signed in.
      'signInSuccess': function(user, credential, redirectUrl) {
        handleSignedInUser(user);
        // Do not redirect.
        return false;
      }
    },
    // Opens IDP Providers sign-in flow in a popup.
    'signInFlow': 'popup',
    'signInOptions': [
      // The Provider you need for your app. We need the Phone Auth
      firebase.auth.TwitterAuthProvider.PROVIDER_ID,
      {
        provider: firebase.auth.PhoneAuthProvider.PROVIDER_ID,
        recaptchaParameters: {
          type: 'image', // another option is 'audio'
          size: 'invisible', // other options are 'normal' or 'compact'
          badge: 'bottomleft' // 'bottomright' or 'inline' applies to invisible.
        }
      }
    ],
    // Terms of service url.
    'tosUrl': 'https://www.google.com'
  };
}