堆叠数据集时在条形图顶部显示最高值(chartjs)

<script src="https://cdn.jsdelivr.net/npm/chart.js"></script>
<script src="https://cdn.jsdelivr.net/npm/chartjs-plugin-datalabels"></script>

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

var ctx = document.getElementById('myChart').getContext('2d');
var myChart = new Chart(ctx, {
    type: 'bar',
    data: {
        labels: ['数据1', '数据2', '数据3'],
        datasets: [{
            label: '数据集1',
            data: [10, 20, 30],
            backgroundColor: 'rgba(255, 99, 132, 0.5)',
            borderColor: 'rgba(255, 99, 132, 1)',
            borderWidth: 1
        }, {
            label: '数据集2',
            data: [15, 25, 35],
            backgroundColor: 'rgba(54, 162, 235, 0.5)',
            borderColor: 'rgba(54, 162, 235, 1)',
            borderWidth: 1
        }]
    },
    options: {
        plugins: {
            datalabels: {
                anchor: 'end',
                align: 'top',
                formatter: function(value, context) {
                    if (context.dataset.data.indexOf(Math.max(...context.dataset.data)) === context.dataIndex) {
                        return value;
                    } else {
                        return '';
                    }
                }
            }
        }
    }
});