JSFiddle - React, Tailwind, and code Playground

by rough cheap

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.7.2/Chart.min.js"></script>
<canvas id="myChart"></canvas>

JavaScript

var ctx = document.getElementById("myChart");

var data = {
  // labels: ["a","b","c","d","e","f"],
  datasets: [{
      data: [10, 20, 20, 30],
      label: 'Data 1',
      labels: ["a", "b", "c", "d"],
      backgroundColor: ['#ff6384', '#36a2eb', '#cc65fe', '#ffce56']
    },
    {
      data: [30, 50],
      label: 'Data 2',
      labels: ["e", "f"],
      backgroundColor: ['#ffffbb', '#0000aa']
    }
  ],
};

var options = {
  tooltips: {
    callbacks: {
      label: function(item, data) {
        console.log(item)
        var label = data.datasets[item.datasetIndex].labels[item.index];
        var value = data.datasets[item.datasetIndex].data[item.index];
        return label + ': ' + value;
      }
    }
  }
};

var pieChart = new Chart(ctx, {
  type: 'pie',
  data: data,
  options: options
})