Basic

const config = { type: 'bar', data, options: { scales: { x: { beginAtZero: true, max: 120, min: 0 }, y: { beginAtZero: true, max: 120, min: 0 } }, plugins: { annotation: { annotations: { annotation1, annotation2, annotation3 } } } } };

const config = {
  type: 'bar',
  data,
  options: {
    scales: {
      x: {
        beginAtZero: true,
        max: 120,
        min: 0
      },
      y: {
        beginAtZero: true,
        max: 120,
        min: 0
      }
    },
    plugins: {
      annotation: {
        annotations: {
          annotation1,
          annotation2,
          annotation3
        }
      }
    }
  }
};

const annotation1 = { type: 'label', borderColor: (ctx) => ctx.chart.data.datasets[0].backgroundColor, borderRadius: 6, borderWidth: 1, content: ['March', 'annotated'], position: { x: 'center', y: 'end' }, xValue: 'March', yValue: (ctx) => yValue(ctx, 'March') };

const annotation1 = {
  type: 'label',
  borderColor: (ctx) => ctx.chart.data.datasets[0].backgroundColor,
  borderRadius: 6,
  borderWidth: 1,
  content: ['March', 'annotated'],
  position: {
    x: 'center',
    y: 'end'
  },
  xValue: 'March',
  yValue: (ctx) => yValue(ctx, 'March')
};

const annotation2 = { type: 'label', borderColor: (ctx) => ctx.chart.data.datasets[0].backgroundColor, borderRadius: 6, borderWidth: 1, content: ['June', 'annotated'], position: { x: 'center', y: 'end' }, xValue: 'June', yValue: (ctx) => yValue(ctx, 'June') };

const annotation2 = {
  type: 'label',
  borderColor: (ctx) => ctx.chart.data.datasets[0].backgroundColor,
  borderRadius: 6,
  borderWidth: 1,
  content: ['June', 'annotated'],
  position: {
    x: 'center',
    y: 'end'
  },
  xValue: 'June',
  yValue: (ctx) => yValue(ctx, 'June')
};

const annotation3 = { type: 'label', borderColor: (ctx) => ctx.chart.data.datasets[0].backgroundColor, borderRadius: 6, borderWidth: 1, content: ['October', 'annotated'], position: { x: 'center', y: 'end' }, xValue: 'October', yValue: (ctx) => yValue(ctx, 'October') };

const annotation3 = {
  type: 'label',
  borderColor: (ctx) => ctx.chart.data.datasets[0].backgroundColor,
  borderRadius: 6,
  borderWidth: 1,
  content: ['October', 'annotated'],
  position: {
    x: 'center',
    y: 'end'
  },
  xValue: 'October',
  yValue: (ctx) => yValue(ctx, 'October')
};

const DATA_COUNT = 12; const MIN = 0; const MAX = 100; const numberCfg = {count: DATA_COUNT, min: MIN, max: MAX}; const data = { labels: ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'], datasets: [{ data: Utils.numbers(numberCfg) }] };

const DATA_COUNT = 12;
const MIN = 0;
const MAX = 100;
const numberCfg = {count: DATA_COUNT, min: MIN, max: MAX};
const data = {
  labels: ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],
  datasets: [{
    data: Utils.numbers(numberCfg)
  }]
};

function yValue(ctx, label) { const chart = ctx.chart; const dataset = chart.data.datasets[0]; return dataset.data[chart.data.labels.indexOf(label)]; }

function yValue(ctx, label) {
  const chart = ctx.chart;
  const dataset = chart.data.datasets[0];
  return dataset.data[chart.data.labels.indexOf(label)];
}