example4.vue

<template>
    <main>
        <h1>Cart Content</h1>
        <p>Total Number of Items: {{totalNumberOfCartItems}}</p>
        <form @submit.prevent="addItemToCart">
            <input type="text" v-model="item" required>
            <button type="submit">Add to cart</button>
        </form>
    </main>
</template>

<script>
export default {
    data() {
        return {
            item: ''
        }
    },
    computed: {
        totalNumberOfCartItems() {
            // Accessing the Vuex state
            return this.$store.getters.totalNumberOfCartItems;
        }
    },
    methods: {
        addItemToCart() {
            // Check that the input field isn't empty
            if(this.item !== '') {
                // commiting the additemtocart mutation with the payload
                this.$store.commit('addItemToCart', this.item)
            }
        }
    }
}
</script>