Vue example for https://medium.com/@l.mugnaini/things-that-can-go-wrong-without-a-strictly-typed-language-d91d418a53a1

vue.html

<div id="app">
    <div v-for="product in products">
        <input type="number" v-model="product.quantity">
        <button @click="product.quantity += 1">
            Add 1
        </button>
        {{ product.name }}
    </div>
    <p>Total Inventory: {{ totalProducts }}</p>
    <p>Quantities: {{products.map(function(p){return p.quantity})}}</p>
</div>
<script src="https://unpkg.com/vue"></script>
<script>
    const app = new Vue({
        el: '#app',
        data: {
            products: []
        },
        computed: {
            totalProducts() {
                return this.products.reduce((sum, product) => {
                    return sum + product.quantity
                }, 0)
            }
        },
        created: function () {
            fetch('https://api.myjson.com/bins/74l63')
                .then(response => response.json())
                .then(json => {
                    this.products = json.products
                })
        }
    })
</script>