title: Datatables: Select row with given ID
body: <p>I've set up a datatables plugin and created a new table from an JSON file:</p>
  
  <pre><code>var table= $("#mytable").DataTable({
  
      ajax: "list.json",
      columns: [
          {"data": "name"},
          {"data": "location"},
          {"data": "date"}
      ]
  }); 
  </code></pre>
  
  <p>Now I want to add an <code>.active</code> class to a row with a given id:</p>
  
  <pre><code>table.on( 'xhr', function () {
    table.row("#id_1").addClass("active");
  }
  </code></pre>
  
  <p>(the id's for the rows has been defined during the plugin setup and are in place). However, I get this error:</p>
  
  <pre><code>undefined is not a function
  </code></pre>
  
  <p>like it can't find a row with this ID, however I do have it. Any ideas?</p>