如何为图表中的每个数据点创建自定义工具提示？答案

【问题标题】：How can I create custom tooltips for each data point in a graph?如何为图表中的每个数据点创建自定义工具提示？
【发布时间】：2020-11-23 17:56:01
【问题描述】：

我有一个堆积条形图，我想在其中显示我们的定性分析师需要完成主题编码过程的项目比例。然而，网页的访问者不一定知道上下文，而只是想要工具提示中的一些细节。我有两个类别：（1）总项目和（2）编码项目。在“剩余项目：170”下的项目总数工具提示的新行中，我想要“描述：尚未定性编码的剩余项目”。同样对于“编码项目：70”，我想要一个新行来显示“描述：已定性编码的项目数量。”

我的堆叠条形图的最后一个工作版本在这里：https://codepen.io/tenebris_silentio/pen/ZEWzXyr

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Portfolio Review Overview</title>
        <script src="https://code.jquery.com/jquery-3.4.1.slim.js"></script>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.16.0/umd/popper.js"></script>
        <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.js"></script>
        <link href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.css" rel="stylesheet"/>
        <link href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.css" rel="stylesheet"/>
    </head>

      <meta name="viewport" content="width=device-width, initial-scale=1">
      <link rel="stylesheet" href="https://www.w3schools.com/w3css/4/w3.css">
      <link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Lato">
      <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">



            <script src='https://cdn.plot.ly/plotly-latest.min.js'></script>

     <div class="container">
         <div class="row my-3">
                <div class="col">
                  <p class="sansserif"><br>
                </div>
            </div>

                <div class="col-md-6 py-1">
                    <div class="card" style="width: 36rem;">
                        <div class="card-body">
                            <canvas id="chBar"></canvas>
                        </div>
                    </div>
                </div>
            </div>

    <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.5.0/Chart.js"></script>

    <script>

    // chart colors
    var colors = ['#007bff','#28a745','#333333','#c3e6cb','#dc3545','#6c757d'];

    /* bar chart */
    var ctx = document.getElementById('chBar');

var myChart = new Chart(ctx, {
  type: 'bar',
  data: {
    labels: ['Proportion of Coded Projects'],
    datasets: [
      {
        label: ['Coded Projects'],
        data: [70],
        info: [
        ['This refers to projects that have not been qualitatively coded using the TDF.'],
        backgroundColor: '#D6E9C6',
      }],
      {
        label: 'Remaining Projects',
        data: [170],
        backgroundColor: colors.slice(0,1),
        info: [
        ['This refers to total number of projects left to code.'],
      },
    ]
  },

  options: {
    tooltips: {
      callbacks: {
        title: (tooltipItems, data) => data.labels[tooltipItems[0].index],
        label: (tooltipItems, data) => 'Count: ' + data.datasets[0].data[tooltipItems.index],
        footer: (tooltipItems, data) => ['', 'Description:'].concat(data.datasets[0].info[tooltipItems[0].index])
      }
    }
    scales: {
      xAxes: [{ stacked: true }],
      yAxes: [{ stacked: true }]
    }
  }
});


    </script>

【问题讨论】：

标签： javascript html css chart.js bar-chart

【解决方案1】：

您的tooltips.callbacks 应如下所示：

tooltips: {
  callbacks: {
    title: (tooltipItems, data) => data.labels[tooltipItems[0].index],
    label: (tooltipItems, data) => data.datasets[tooltipItems.datasetIndex].label + ' ' + data.datasets[tooltipItems.datasetIndex].data[tooltipItems.index],
    footer: (tooltipItems, data) => ['', 'Description:'].concat(data.datasets[tooltipItems[0].datasetIndex].info)
  }
}

请在下面查看您修改后的代码：

var colors = ['#007bff', '#28a745', '#333333', '#c3e6cb', '#dc3545', '#6c757d'];

var ctx = document.getElementById('chBar');
new Chart(ctx, {
  type: 'bar',
  data: {
    labels: ['Proportion of Coded Projects'],
    datasets: [{
        label: 'Coded Projects',
        data: [70],
        backgroundColor: '#D6E9C6',
        info: [
          ['This refers to projects that have not'],
          ['been qualitatively coded using the TDF.']
        ]
      },
      {
        label: 'Remaining Projects',
        data: [170],
        backgroundColor: colors.slice(0, 1),
        info: [
          ['This refers to total number'],
          ['of projects left to code.']
        ]
      }
    ]
  },
  options: {
    tooltips: {
      callbacks: {
        title: (tooltipItems, data) => data.labels[tooltipItems[0].index],
        label: (tooltipItems, data) => data.datasets[tooltipItems.datasetIndex].label + ' ' + data.datasets[tooltipItems.datasetIndex].data[tooltipItems.index],
        footer: (tooltipItems, data) => ['', 'Description:'].concat(data.datasets[tooltipItems[0].datasetIndex].info)
      }
    },
    scales: {
      xAxes: [{
        stacked: true
      }],
      yAxes: [{
        stacked: true
      }]
    }
  }
});

canvas {
  max-width: 400px;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.3/Chart.min.js"></script>
<canvas id="chBar"></canvas>

【讨论】：

啊，现在我知道我哪里出错了。非常感谢！