[Vuejs]-How to use in imported function in template?

You could add it to your component:

import { addZeroes } from "../../../js/helpers";

export default {
    data() {
        return {
            // populated via AJAX
            restaurants: [
                {
                    categories: []
                }
            ],
        }
    },
    methods: {
        addZeroes // shorthand for addZeroes: addZeroes
    }
}