JavaScript example for responding to Cognito's SRP authentication challenges

There's a python example here. Does anyone have a link to an example for JavaScript?

Alternatively, can anyone provide guidance on how to access the functions inside AuthenticationHelper.js (to build the SRP challenge responses during authentication) per this AWS knowledge article?

SRP_A = g^a (mod N)

Use g as defined in AuthenticationHelper.js on the AWS Amplify (JavaScript) GitHub repository.