I have that problem. I have a server running a system in PHP only with jQuery ... etc. Simple things, but lately I decided to update my site to Vue and I started to make the Login.
My experience with Vue is good, I did it through vue-cli and webpack and I have my dev and my built. But I want to integrate Google Oauth ... I found this google package oauth and it works perfectly.
My problem is that in dev mode I can not see it, as is the operation of Google Oauth. Well run on my localhost: 8080 and not on link
That is, in the dev mode in my localhost the Google Oauth does not work, because it says: Not a valid origin for the client: http://localhost:8080 has not been whitelisted for client ID XXXXXXXXXXXXX
But when I go to build and upload it to my site in /login/ there if it shows.
Any way to see the Google Oauth in dev mode from somewhere on my site? For example: https://www.misitio.com/dev/login/