title: Array of jquery DataTables objects gives type errors
body: <p>I'm dynamically generating tables and every time I generate one, I create a corresponding DataTable object, which I store in an array.</p>
  
  <pre class="lang-js prettyprint-override"><code>tables1 = {};
  </code></pre>
  
  <p>I create the objects and get the values like so (posterized for easy viewing):</p>
  
  <pre class="lang-js prettyprint-override"><code>categoryIds.each( function ( value, index ) {
       tables1[value]=jQuery('#tbl' + category_id).DataTable();
  });
  
  jQuery.ajax({
      url: url,
      type: 'get',
      }).done(function(data) {
          object = jQuery.parseJSON(data);
          object.each(function(value, index) {
              tables1[value.catid].row.add([value.id, value.title]);
          });
  
          categoryIds.each( function ( value, index ) {
              tables1[value].draw();
              //typeerror here
          }
  });
  </code></pre>
  
  <p>The above gives me a <code>Uncaught TypeError: Cannot read property 'length' of undefined</code> error, but works if I surround it with try catches.</p>
  
  <p>Once I've created the tables and want to wipe them, even this simple function is giving me an typeerror:</p>
  
  <pre class="lang-js prettyprint-override"><code>jQuery.each(tables1, function ( index, value) {
      tables1[index].clear().draw();
  } );
  </code></pre>
  
  <p>I'm using DataTables 1.10, and googling this error seems to pop up mostly when dealing with ajax data sources, which I'm not using.</p>