title: Multiply the object properties
body: <p>someone tell me how to multiply object's properties? I need this object multiplied by the count of property price and put together</p>
  
  <pre><code>var menu = [  
         {  
            "id": 5,
            "price": 13,
            "count": 2
         },
         {  
            "id": 8,
            "price": 7,
            "count": 3
         },
         {
              "id": 9,
              "price": 17,
              "count": 1
         }
      ]
  
  var sum = 0;
  for (var key in menu) {
      for (var key1 in menu[key]) {
          //console.log(key1);
          if (key1 == 'price'){
              price += menu[key][key1];
          }
  
      }
  
  }
  </code></pre>
  
  <p>but I have no idea how to multiply count property</p>