How to count values in an json object array? (In V

Question

i'm trying to sum up a couple of properties in an object. I'm using a VueJS filter, in combination with the ES5 reduce function to add up the numbers to get a total.

Well, it's not working at this moment. Somebody care to help me out?

new Vue({
  el: '.app',
  data: {
    products: [{
      "pid": "37",
      "pname": "Reprehenderit",
      "price": "4.29",
      "amount": "1"
    }, {
      "pid": "45",
      "pname": "Sit",
      "price": "1.00",
      "amount": "4"
    }, {
      "pid": "67",
      "pname": "Omnis",
      "price": "7.00",
      "amount": "2"
    }],
  }
});

Vue.filter('subtotal', function (list, key1, key2) {
    return list.reduce(function(total, item) {
        return total + item.key1 * item.key2
    }, 0)
})

<script src="http://cdnjs.cloudflare.com/ajax/libs/vue/1.0.11/vue.min.js"></script>

<div class="app">
  
  Product example: {{ products[0].pname }}
  
  <br><br>
  
  Total: {{ products | subtotal 'price' 'amount' }}

</div>

Answer 1

Looks like your event handler is being initialized after the vue is already constructed. If your events aren't attached when they're called they'll be ignored.

Also, you can't reference your object properties like that product.variable you'll need to use product[variable]

Vue.filter('subtotal', function (list, key1, key2) {
    return list.reduce(function(total, item) {
        return total + item[key1] * item[key2]
    }, 0)
})

new Vue({
  el: '.app',
  data: {
    products: [{
      "pid": "37",
      "pname": "Reprehenderit",
      "price": "4.29",
      "amount": "1"
    }, {
      "pid": "45",
      "pname": "Sit",
      "price": "1.00",
      "amount": "4"
    }, {
      "pid": "67",
      "pname": "Omnis",
      "price": "7.00",
      "amount": "2"
    }],
  }
});

<script src="http://cdnjs.cloudflare.com/ajax/libs/vue/1.0.11/vue.min.js"></script>

<div class="app">
  
  Product example: {{ products[0].pname }}
  
  <br><br>
  
  Total: {{ products | subtotal 'price' 'amount' }}

</div>

Answer 2

You could get the value of key like this:

return total + item[key1] * item[key2]

Also, you should set the filter before the vue instance.