performAuthorizationAndTokenRequest.ts

 let authRequestExtras = {
   code_challenge: this._verifier.challenge,
   code_challenge_method: this._verifier.method
 }
 
  let authResponse = this.authorizationHandler.performAuthorizationRequest(this.configuration, new AuthorizationRequest(
    clientId, redirectUri, scope, AuthorizationRequest.RESPONSE_TYPE_CODE,
    undefined /* state */, authRequestExtras));

  let tokenRequestExtras = = { code_verifier: this._verifier.verifier };

  let tokenResponse = this.authorizationHandler.performTokenRequest(
     authConfig,
     new TokenRequest(clientId, redirectUri, GRANT_TYPE_AUTHORIZATION_CODE, authResponse.response.code, undefined, tokenRequestExtras));
    

do you have full working example with PKCE