谷歌图表时间轴-获取行鼠标单击文本

google.charts.load('current', {
  callback: function () {
    var dataTable = new google.visualization.DataTable();
    dataTable.addColumn({ type: 'string', id: 'President' });
    dataTable.addColumn({ type: 'date', id: 'Start' });
    dataTable.addColumn({ type: 'date', id: 'End' });
    dataTable.addRows([
      [ 'Washington', new Date(1789, 3, 30), new Date(1797, 2, 4) ],
      [ 'Adams',      new Date(1797, 2, 4),  new Date(1801, 2, 4) ],
      [ 'Jefferson',  new Date(1801, 2, 4),  new Date(1809, 2, 4) ]]);

    var container = document.getElementById('timeline');
    var chart = new google.visualization.Timeline(container);

    google.visualization.events.addListener(chart, 'select', function () {
      selection = chart.getSelection();
      if (selection.length > 0) {
        console.log(dataTable.getValue(selection[0].row, 0));
      }
    });

    chart.draw(dataTable);
  },
  packages: ['timeline']
});

<script src="https://www.gstatic.com/charts/loader.js"></script>
<div id="timeline"></div>

google.charts.load('current', {
  callback: function () {
    var dataTable = new google.visualization.DataTable();
    dataTable.addColumn({ type: 'string', id: 'President' });
    dataTable.addColumn({ type: 'date', id: 'Start' });
    dataTable.addColumn({ type: 'date', id: 'End' });
    dataTable.addRows([
      [ 'Washington', new Date(1789, 3, 30), new Date(1797, 2, 4) ],
      [ 'Adams',      new Date(1797, 2, 4),  new Date(1801, 2, 4) ],
      [ 'Jefferson',  new Date(1801, 2, 4),  new Date(1809, 2, 4) ]]);

    var container = document.getElementById('timeline');
    var chart = new google.visualization.Timeline(container);

    var saveRows = [];
    google.visualization.events.addListener(chart, 'ready', function () {
      chartRows = container.getElementsByTagName('rect');
      Array.prototype.forEach.call(chartRows, function(row) {
        if ((parseInt(row.getAttribute('x')) === 0) && (row.getAttribute('fill') !== 'none')) {
          saveRows.push(row);
          row.addEventListener('click', function (e) {
            for (var i = 0; i < saveRows.length; i++) {
              if (e.target === saveRows[i]) {
                getRowLabel(i);
                break;
              }
            }
          }, false);
        }
      });
    });

    google.visualization.events.addListener(chart, 'select', function () {
      selection = chart.getSelection();
      if (selection.length > 0) {
        getRowLabel(selection[0].row);
      }
    });

    function getRowLabel(index) {
      console.log(dataTable.getValue(index, 0));
    }

    chart.draw(dataTable);
  },
  packages: ['timeline']
});

<script src="https://www.gstatic.com/charts/loader.js"></script>
<div id="timeline"></div>