title: Dynamic data loading in Google Charts
body: <p>I have a google chart which I am feeding with JSON data as follows:</p>
  
  <pre><code>      var visualization;
        var chart_url = 'http://XXappspot.com/data?v=load1&amp;v=load5&amp;v=load15&amp;span=100';
  
        function drawVisualization() {
          var query = new google.visualization.Query(chart_url);
          query.send(handleQueryResponse);
        }
  
        function handleQueryResponse(response) {
          if (response.isError()) {
            alert('Error in query: ' + response.getMessage() + ' ' + response.getDetailedMessage());
            return;
          }
  
          var data = response.getDataTable();
          var formatter = new google.visualization.DateFormat( { pattern: 'd MMM, HH:mm:ss' } );
          formatter.format(data, 0);
          visualization = new google.visualization.LineChart(document.getElementById('visualization'));
          visualization.draw(data, { hAxis: { format: "HH:mm" }});
        }
  
        google.setOnLoadCallback(drawVisualization);
  </code></pre>
  
  <p>Now I would like to add buttons on the page which will change the data source (request other data) and refresh the chart. I have seen the use of controls in the documentation but they seem to work only with data already downloaded, while I would like to re-download different data. Any ideas how to do this?</p>
  
  <p>Bonus question: is there a way to change the timezone of the X axis? No, adding "timeZone" to the hAxis options does not work. Preferably, I would like to show datetime data in the local timezone of the user.</p>