title: Sum and group data from object
body: <p>As title , I have a problem with processing data</p>
  
  <p>example data :</p>
  
  <pre><code>[
   {detail: { '60': 300, '80': 200 }},
   {detail: { '60': 100, '68': 222 }}
  ]
  </code></pre>
  
  <p>how do i process those data become like this :</p>
  
  <pre><code>"60" : {
   "sum" : 400,  // value
   "count" : 2
  },
  "80" : {
   "sum" : 200,
   "count" : 1
  },
  "68" : {
   "sum" : 222,
   "count" : 1
  },
  </code></pre>