Hi,
Thank you for reaching out to the Google Ads API support team.
I understand that you want to retrieve the encoded session token from Google's Javascript code in the browser. Unfortunately, javascript client library is not yet supported by the Google Ads API, but we already raised this to the wider team, and they mentioned that, you may refer to this
client library that exists. Our team also mentioned that this is a third party client library, and they work closely with them to ensure it stays up to date. Also, to retrieve the encoded session token, you may use this
link to raise this concern.
Hope this helps.
Regards,
Google Ads API Team.