title: Number of items in a json array
body: <p>Looking for a simple bit of JS to count the number of items in a .json file (each item represents, in this case, an instagram photo being pulled into the web app; I want to count the number of photos). Json is structured thusly...</p>
  
  <pre><code>{
   "type":"FeatureCollection",
   "features":[
    {
       "type":"Feature",
       "geometry":{
          "coordinates":[
             -79.40916,
             43.87767
          ],
          "type":"Point"
       },
       "properties":{
          "longitude":-79.40916,
          "latitude":43.87767,
          "title":"",
          "user":"cmay2400",
          "id":"176051485697457528_13947894",
          "image":"http:\/\/distilleryimage0.instagram.com\/1d725a3a8d7511e181bd12313817987b_7.jpg",
          "images":{
             "low_resolution":{
                "url":"http:\/\/distilleryimage0.instagram.com\/1d725a3a8d7511e181bd12313817987b_6.jpg",
                "width":306,
                "height":306
             },
             "thumbnail":{
                "url":"http:\/\/distilleryimage0.instagram.com\/1d725a3a8d7511e181bd12313817987b_5.jpg",
                "width":150,
                "height":150
             },
             "standard_resolution":{
                "url":"http:\/\/distilleryimage0.instagram.com\/1d725a3a8d7511e181bd12313817987b_7.jpg",
                "width":612,
                "height":612
             }
          },
          "description":"Today's ride &lt;span class=\"tag\"&gt;#zipcar&lt;\/span&gt;",
          "instagram_id":"13947894",
          "likes":1,
          "profile_picture":"http:\/\/images.instagram.com\/profiles\/profile_13947894_75sq_1322267355.jpg"
       }
    },
    {
       "type":"Feature", [...]
  </code></pre>
  
  <p>I just want to loop through the json file and count the number of items. Completely lost on where to begin.</p>