Gets the username for the current user using the SSO API

getUsername.js

export async function getUserName() {
  try {
      let tokenData = await OfficeRuntime.auth.getAccessToken({ allowSignInPrompt: false, forMSGraphAccess: true });
      var parts = tokenData.split(".");
      var token = JSON.parse(atob(parts[1]));
      return token.preferred_username;
  }
  catch (exception) {
    console.log(exception.message);
  }
}