问动画谷歌图表转换多次

EN

    <script type="text/javascript">
      var options;
      var chart;
      google.load("visualization", "1", {packages:["corechart"]});
      google.setOnLoadCallback(prep);
      function prep(){
        chart = new google.visualization.LineChart(document.getElementById('chart'));
        options = {
            colors: ['Red','Purple','Blue'],
            animation:{duration: 1000,easing: 'linear'}
        };
        drawChart();
      }
      function triggerChart(data){
        chart.draw(data, options);
      }
      function drawChart(){

        data = google.visualization.arrayToDataTable([
          ['Hour', 'First', 'Second', 'Third'],
          [1,1,2,3],
          [2,2,3,4]
        ]);
        triggerChart(data);

        data = google.visualization.arrayToDataTable([
          ['Hour', 'First', 'Second', 'Third'],
          [3,2,3,4],
          [4,5,6,7]
        ]);
        setTimeout(function(){triggerChart(data);},2000);

        data = google.visualization.arrayToDataTable([
          ['Hour', 'First', 'Second', 'Third'],
          [5,5,6,7],
          [6,7,8,9]
        ]);
        setTimeout(function(){triggerChart(data);},4000);

        data = google.visualization.arrayToDataTable([
          ['Hour', 'First', 'Second', 'Third'],
          [7,11,12,13],
          [8,12,13,14]
        ]);
        setTimeout(function(){triggerChart(data);},6000);
      }
    </script>
    <div id="chart" style="width:900px;height:600px"></div>