How babel really works with Vue?


My question isn’t really about Vue but i think here i can have some help about babel and how he polyfill Vue.

I’m using Vue on SharePoint and i can’t use npm in order to install packages.

I need to use babel polyfill if i want use Vue with Internet explorer (SharePoint need it).

Everything fine with Vue and babel but i can’t write my own class when i’m using IE? How can i use babel for my own code ?

That why i want to know how Vue using babel to work with IE.

Thanks for your reply.

Best regards