javascript - 获取 Google 可视化饼图中的点击标签 [corechart]

Question

如何在 Google 可视化饼图 [corechart] 中获取点击的标签名称？即，如何使用 getSelection()？

      google.load("visualization", "1", {packages:["corechart"]});
  google.setOnLoadCallback(drawChart);
  function drawChart() {
    var data = new google.visualization.DataTable();
    data.addColumn('string', 'Task');
    data.addColumn('number', '');
    data.addRows(6);
    data.setValue(0, 0, 'Demographics');
    data.setValue(0, 1, 1);
    data.setValue(1, 0, 'Behavior');
    data.setValue(1, 1, 1);
    data.setValue(2, 0, 'Campaign');
    data.setValue(2, 1, 1);
    data.setValue(3, 0, 'Purchases');
    data.setValue(3, 1, 1);
    data.setValue(4, 0, 'Social');
    data.setValue(4, 1, 1);
    data.setValue(5, 0, 'Support');
    data.setValue(5, 1, 1);

    var chart = new google.visualization.PieChart(document.getElementById('chart_div'));
    chart.draw(data, {width: 500, height: 500, pieSliceText: 'label', legend: 'none', is3D: true,
        colors: ['#000033', '#00004D', '#000066', '#000080', '#333399' , '#00001A'],
        });
    google.visualization.events.addListener(chart, 'select', selectHandler);
    function selectHandler(e) {
        alert("Need to get clicked pie slice");
  }
}

Answer 1

    google.visualization.events.addListener(chart, 'select', function(e) {
        var selection = chart.getSelection();
        alert(pieSlice[selection[0].row]);

    });