How can i get the index of the previous slide?

Question

How can i get the index of the previous slide?

I am using the following code:

var glide = new Glide('.glide', {})
var prevIndex = null

glide.on('run.before', () => {
   prevIndex = glide.index
})

glide.mount()

Is there an easier way to get the index of the previous slide?