Login with aws cognito and federated identities.js

//-----------------------------------------------//
//On page load 
// - Browser -
//-----------------------------------------------//

AWS.config.update({
  region: "eu-west-1"
});

var credConfig = {
  IdentityPoolId: "XXXXX-XXX-XXX"
  Logins:{}
};
//Do we have a token stored from a previous login? 
if(localStorage.getItem('Token')){
  //If using Federated Logins, use `cognito-identity.amazonaws.com`
  credConfig.Logins["cognito-identity.amazonaws.com"] = localStorage.getItem('Token');
}
AWS.config.update({
  credentials: new AWS.CognitoIdentityCredentials(credConfig)
});


//-----------------------------------------------//
//Upgrade local CognitoIdentityCredentials after successful 
//Login with Lambda & Federated Identities
// - Browser -
//-----------------------------------------------//

onLoginApiResponse(apiResponse) {
  AWS.config.update({
    credentials: new AWS.CognitoIdentityCredentials({
      IdentityId: apiResponse.IdentityId,
      Logins: {
        "cognito-identity.amazonaws.com": apiResponse.Token
      }
    })
  });
  //Save the retrieved Token for next page refresh
  localStorage.setItem('Token', apiResponse.Token);
}

//#############################################################################//


//-----------------------------------------------//
//Example Lambda Cognito Identity upgrade after 
//successful login
// - Lambda -
//-----------------------------------------------//

exports.handler = function(event, context, callback){
  //Some login function
  DoSomeSortOfLogin();
  
  //Success...
  var cognitoidentity = new AWS.CognitoIdentity();
  var cognitoParams = {
      IdentityPoolId: "XXXXX-XXX-XXX",
      Logins: {},
      TokenDuration: 7200
  };

  //User Id from our local DB
  cognitoParams.Logins["developer.provider.name.set.in.cognito.config"] = "123456";

  //Use current cognito identity if available
  if(context.identity && context.identity.cognitoIdentityId){
      cognitoParams.IdentityId = context.identity.cognitoIdentityId;
  }

  //Get a Token from Cognito so that the browser can upgrade to an authorised user
  cognitoidentity.getOpenIdTokenForDeveloperIdentity(cognitoParams, callback);
}