google.setOnLoadCallback(drawChart);
function drawChart() {
var data = google.visualization.arrayToDataTable([
['Category', 'Value'],
['Videos', 1000],
['Mail', 1170]
]);
var chart = new google.visualization.BarChart(document.getElementById('chart_div'));
google.visualization.events.addListener(chart, 'select', function(){
var selection=chart.getSelection();
if(selection.length == 1){
var row = selection[0].row;
var col = selection[0].column;
var cat = data.getValue(row,0);
drawSubChart(cat);
}
})
chart.draw(data, {});
}
function drawSubChart(cat){
var arr = [['SubCategory', 'Value']];
if(cat == 'Videos'){
arr.push(['Youtube', 700], ['DailyMotion', 300]);
}else if(cat == 'Mail'){
arr.push(['Gmail', 600], ['Hotmail', 570]);
}
var data = google.visualization.arrayToDataTable(arr);
var chart = new google.visualization.BarChart(document.getElementById('chart_div2'));
chart.draw(data, {});
}
<script type="text/javascript" src="https://www.google.com/jsapi?autoload={'modules':[{'name':'visualization','version':'1','packages':['corechart']}]}"></script>
<div id="chart_div" style="width: 500px; height: 300px;"></div>
<div id="chart_div2" style="width: 500px; height: 300px;"></div>