title: DC.js numberDisplay with crossfilter get total records
body: <p>I am trying to understand how to use crossfilter with dc.js. I have the following data and I would just like to start by populating a numberDisplay with the total number of objects within the data. Then secondly populating how many records there are for bills losses.</p>
  
  <pre><code>var data = [
    {
      "team": "bills",
      "location": "home",
      "outcome": "loss"
    },
    {
      "team": "dolphins",
      "location": "away",
      "outcome": "loss"
    },
    {
      "team": "jets",
      "location": "home",
      "outcome": "loss"
    },
    {
      "team": "jets",
      "location": "home",
      "outcome": "win"
    },
    {
      "team": "dolphins",
      "location": "home",
      "outcome": "loss"
    },
    {
      "team": "dolphins",
      "location": "away",
      "outcome": "win"
    },
    {
      "team": "dolphins",
      "location": "home",
      "outcome": "win"
    },
    {
      "team": "dolphins",
      "location": "away",
      "outcome": "loss"
    }
  ]
  </code></pre>
  
  <p>DC.JS numberDisplay takes a group but I have not been able to figure out how to simply count the number of records to start with.</p>
  
  <pre><code>var cf = crossfilter(data);
  var team = cf.dimension(function(d) { return d.team })
  var teams = team.group().reduceCount();
  </code></pre>
  
  <p>this seems to only return the value for the first key? reduceSum() and groupAll() haven't worked either. </p>
  
  <pre><code>var numberDisplayElem = dc.numberDisplay("#number-display-elem");
      numberDisplayElem
          .group(teams);
  </code></pre>
  
  <p>Basically just trying to get the total to populate the numberDisplay, and then a single numberBack of filtered values like total bills losses, etc. Having trouble getting started. TIA.</p>