使用chart.js在工具提示中显示两个值

<script src="path/to/chart.js"></script>

<canvas id="myChart"></canvas>

var ctx = document.getElementById('myChart').getContext('2d');

var data = {
  labels: ['Label 1', 'Label 2', 'Label 3'],
  datasets: [{
    label: 'Dataset 1',
    data: [10, 20, 30]
  }, {
    label: 'Dataset 2',
    data: [15, 25, 35]
  }]
};

var myChart = new Chart(ctx, {
  type: 'bar',
  data: data,
  options: {
    tooltips: {
      callbacks: {
        title: function(tooltipItem, data) {
          return data.labels[tooltipItem[0].index];
        },
        label: function(tooltipItem, data) {
          var datasetLabel = data.datasets[tooltipItem.datasetIndex].label || '';
          return datasetLabel + ': ' + tooltipItem.yLabel;
        }
      }
    }
  }
});