title: jQuery "TypeError: invalid 'in' operand a"
body: <p>I have the following json array returning from an ajax call:</p>
  
  <p><code>{"err":"err_type","fields":["field1","field2"]}</code></p>
  
  <p>when tryin to print it out with this function:</p>
  
  <pre><code>$.each(data.fields, function (i, field) {
      console.log(field);
      $.each(field, function (j, f) {
          $('[name="'+f+'"]').addClass('form_err');
          console.log(f);
      });
  });
  </code></pre>
  
  <p>i get this:</p>
  
  <pre><code>data1
  
  TypeError: invalid 'in' operand a
  ...turn function(b){return db(a,b).length&gt;0}}),contains:fb(function(a){return funct...
  </code></pre>
  
  <p>and so i can't figure out how to use this array! Anyone have any idea?</p>