I've had a really bad time looking for a solution for this. The only thing that I was able to make for for getting the listening key, was adding this extension to my browser https://chrome.google.com/webstore/detail/allow-cors-access-control/lhobafahddgcelffkeicbaginigeejlf/related?hl=es
I came across some other solutions, like some extra dependencies (axios, for example) or running a proxy server (light-server,or lite-server, or some nodejs-proxy-server), but I was not able to make those work in time really.
With that extension I was able to get some information about the Request and Response given to/from the server using DevTools from Chrome. Do you think it may be possible to get some information from those headers I can use in my raw code? So I can get rid of that extension. I tried to use some of the key-value pairs I considered to be part of the solution, eve