title: Fill Javascript object with fixed length multidimensional array
body: <p>I am trying to wrap my head around javascript objects and arrays. I attempted to fill and access an object as following:</p>
  
  <pre><code>obj_keys = [1,2,3,4,5,6,7];
  o = {};
  
  $.each(obj_keys, function(k, v){
      o[v] = [];
      for(var c; c &lt; 10; c++){
          o[v][c] = [];
          o[v][c].push([11,12,13,14]);
      }
  });
  
  console.log(o); 
  </code></pre>
  
  <p>Object { 1: Array[10], 2: Array[10], 3: Array[10], 4: Array[10], 5: Array[10], 6: Array[10], 7: Array[10] }</p>
  
  <pre><code>console.log(o[7]);
  </code></pre>
  
  <p>Array [ ]</p>
  
  <pre><code>console.log(o[7][8]);
  </code></pre>
  
  <p>undefined</p>
  
  <pre><code>console.log(o[7][8][3]);
  </code></pre>
  
  <p>TypeError: o[7][8] is undefined</p>
  
  <p>Why <strong>o[v] = [ ];</strong> is OK, yet <strong>o[v][c] = [ ];</strong> in my for(;;) loop is not?</p>