[Vuejs]-Conditional Component variable value increment Vue/Laravel

A computed property can be used if the deliver_later_num is only dependent on the presence/absence of deliver_today on elements of items array

 cartContent = new Vue({
    el: '#cartList',
    data: {
        items: {}
    },

    computed: {
        deliver_later_num() {
            let num = 0;
            Object.keys(this.items).forEach(key => {
                let item = this.items[key];
                Object.keys(item).forEach(k => {
                    if(k === 'deliver_today' && item[k]) {
                        num++;
                    }
                });
            });

            return num;
         },
    }