在Chart.js v2.7.1中的条形图顶部显示数据

// 引入Chart.js库
import Chart from 'chart.js';

// 创建Canvas元素
const canvas = document.createElement('canvas');
document.body.appendChild(canvas);

// 创建条形图的配置对象
const config = {
  type: 'bar',
  data: {
    labels: ['A', 'B', 'C', 'D'],
    datasets: [{
      label: 'Data',
      data: [10, 20, 30, 40],
      backgroundColor: 'rgba(0, 123, 255, 0.5)'
    }]
  },
  options: {
    plugins: {
      afterDraw: function(chart) {
        const ctx = chart.ctx;
        chart.data.datasets.forEach(function(dataset, datasetIndex) {
          const meta = chart.getDatasetMeta(datasetIndex);
          meta.data.forEach(function(bar, index) {
            const data = dataset.data[index];
            const x = bar._model.x;
            const y = bar._model.y;
            ctx.fillStyle = 'black';
            ctx.fillText(data, x, y - 5);
          });
        });
      }
    }
  }
};

// 创建条形图
new Chart(canvas, config);