[Vuejs]-Can I use the 'index' argument in 'v-for' nested in a 'method'?

Update: based on your need to use it, this is clearly an X-Y problem. You should be using computed properties instead:

computed: {
    filteredSharesByCount: function() {
        return this.shares.filter(share => share.count > 0);
    }
}

You can then reference it as such in your template:

Outdated answer:

The index is accessible as the second optional argument in the v-for binding:

v-for also supports an optional second argument for the index of the current item.

ie:

<div v-for="(share, idx) in sharesPurchased(shares)" :key="share">

Then, within the loop you can simply use idx if you want a method to have access to the index.