How to use the hellojs.on function in hellojs

return true
        },
        form: false
      }
    });

    // Configure application details
    hello.init({ azureAD: backendClientID }, {
      redirect_uri: redirectUrl,
      scope: `openid https://${tenantName}.onmicrosoft.com/${backendClientApiID}/${backendClientScopeName}`,
      response_type: 'token id_token',
      resource: `${backendClientApiID}`,
      display: 'page',
    });

    hello.on('auth.login', (auth) => {
      this.handleAuthLogin(auth);
    });

  }

hello.init({

  aad: {
    name: 'Azure Active Directory',
    oauth: {
      version: 2,
      auth: 'https://login.microsoftonline.com/common/oauth2/v2.0/authorize',
      grant: 'https://login.microsoftonline.com/common/oauth2/v2.0/token'
    },
    scope_delim: ' ',
    form: false
  }
});

hello.on('auth.login', function (auth){
  localStorage.auth = angular.toJson(auth.authResponse);
});