Untitled

<script type="text/javascript">

     // Load the Visualization API and the piechart,table package.

// Create our data table out of JSON data loaded from server.
var piechartdata = new google.visualization.DataTable(jsonPieChartData);

var x = piechartdata.getNumberOfRows();
   alert('Números de linhas é '+x);

// Instantiate and draw our pie chart, passing in some options.
var chart = new google.visualization.LineChart(document.getElementById('chart_div'));
chart.draw(piechartdata, {
  width: 800,
  height: 500,
   animation: {
    duration: 1000,
    easing: 'in'
  }
  /*chartArea: { left:"10%",top:"10%",width:"90%",height:"90%" }*/
});

}

<meta charset="UTF-8">
    <title></title>
</head>
<body>

    <form> <!--method="post" action="criaChart.php"-->
        <select name="op" id="op" class="op"  onchange="drawItems(this.value)">
           <option value="">Escolha</option>
           <option value="Tung">Tungsten</option>
           <option value="Zire 21">Zire 21</option>
           <option value="Zire 72">Zire 72</option>
           <option value="PC H4150">PC H4150</option>
           <option value="PC H2210">PC H2210</option>
           <option value="PC H1930">PC H1930</option>
           <option value="PC RZ1710">PC RZ1710</option>
           <option value="Sony VZ90">Sony VZ90</option>
           <option value="Sony TJ37">Sony TJ37</option>
           <option value="Sony  TH55">Sony TH55</option>

       </select>

    </form>
    <div id="chart_div">

    </div>


</body>