Check if a user is part of a Cognito group in AWS Amplify

If you're looking to understand if an authenticated user is in a specific group the following method may help:

import { Auth } from 'aws-amplify';

const user =  await Auth.currentAuthenticatedUser();

// Returns an array of groups
const groups = user.signInUserSession.accessToken.payload["cognito:groups"];

user.signInUserSession.accessToken.payload["cognito:groups"] returns an array of all the groups the user belongs to.

To discover if a user is part of the admin group use the array includes method:

const groups = user.signInUserSession.accessToken.payload["cognito:groups"];

groups.includes('admin'); // true

For IE and older browsers use indexOf:

const groups = user.signInUserSession.accessToken.payload["cognito:groups"];

groups.indexOf('admin') !== -1; // true

Happy days!