Glyphicons no longer supported in Bootstrap 4

I've read, from official docs, that Glyphicons were dropped from Bootstrap 4.

Today, in my searching for implementing checbox button, I've found one snippet that I appreciate very much:

Snippet for Checkbox 3.0

The problem is that this version is for Bootstrap 3.0, where Glyph were supported yet.

So I've 2 question:

1. Wich is a good alternative to Glyphicons? Or there is a way to use them yet?
2. How I may change the html and js snippet above to make it working wuth Bootstrap 4?