title: How to get length string json in js or jQuery
body: <p>i have this code,</p>
  
  <pre><code>buildSelect: function (data) {
    var response = $.parseJSON(data);
  
  
    alert(response.length);
    var s = "&lt;select&gt;";
    if (response &amp;&amp; response.length) {
      for (var i = 0, l = response.length; i &lt; l; i++) {
        var ri = response[i];
        s += '&lt;option value="' + ri.CUSTOMS_ID + '"&gt;' 
             + ri.CUSTOMS_NAME + '&lt;/option&gt;';
      }
    }
    return s + "&lt;/select&gt;";
  }
                      },
  </code></pre>
  
  <p>i want check response  is n't null or empty and get length i write this code <code>response.length</code>
  but return <code>undifine</code><br/>
  and data return </p>
  
  <pre><code>{"rows":[{"id":1,"cell":["1","بندرامام خميني","IMAM KHOMEINI PORT","True",null]},{"id":2,"cell":["2","آبادان","ABADAN","True",null]},{"id":3,"cell":["3","خرمشهر","KHORRAMSHAHR","True",null]},{"id":4,"cell":["4","بندرعباس","BANDAR ABBAS","True",null]},{"id":5,"cell":["5","بوشهر","BUSHEHR","True",null]},{"id":6,"cell":["6","تهران","TEHRAN","True",null]},{"id":7,"cell":["7","شيراز","SHIRAZ","True",null]},{"id":8,"cell":["8","دبي","DUBAI","True",null]}],"Page":0,"Total":0,"Records":0}
  </code></pre>
  
  <p>i want if Rows isn't empty all child add to DropDownlist</p>
  
  <p>plese help me, thanks</p>