Lower and upper bounds

const config = { type: 'line', data, options: { scales: { y: { stacked: true } }, plugins: { annotation: { annotations: { annotation1, annotation2 } } } } };

const config = {
  type: 'line',
  data,
  options: {
    scales: {
      y: {
        stacked: true
      }
    },
    plugins: {
      annotation: {
        annotations: {
          annotation1,
          annotation2
        }
      }
    }
  }
};

const annotation1 = { type: 'line', borderColor: 'black', borderWidth: 3, label: { enabled: true, backgroundColor: 'black', borderColor: 'black', borderRadius: 10, borderWidth: 2, content: (ctx) => 'Lower bound: ' + minValue(ctx).toFixed(3), rotation: 'auto' }, scaleID: 'y', value: minValue };

const annotation1 = {
  type: 'line',
  borderColor: 'black',
  borderWidth: 3,
  label: {
    enabled: true,
    backgroundColor: 'black',
    borderColor: 'black',
    borderRadius: 10,
    borderWidth: 2,
    content: (ctx) => 'Lower bound: ' + minValue(ctx).toFixed(3),
    rotation: 'auto'
  },
  scaleID: 'y',
  value: minValue
};

const annotation2 = { type: 'line', borderWidth: 3, borderColor: 'black', label: { enabled: true, backgroundColor: 'black', borderColor: 'black', borderRadius: 10, borderWidth: 2, content: (ctx) => 'Upper bound: ' + maxValue(ctx).toFixed(3), rotation: 'auto' }, scaleID: 'y', value: maxValue };

const annotation2 = {
  type: 'line',
  borderWidth: 3,
  borderColor: 'black',
  label: {
    enabled: true,
    backgroundColor: 'black',
    borderColor: 'black',
    borderRadius: 10,
    borderWidth: 2,
    content: (ctx) => 'Upper bound: ' + maxValue(ctx).toFixed(3),
    rotation: 'auto'
  },
  scaleID: 'y',
  value: maxValue
};

function minValue(ctx) { const dataset = ctx.chart.data.datasets[0]; const min = dataset.data.reduce((max, point) => Math.min(point, max), Infinity); return isFinite(min) ? min : 0; } function maxValue(ctx) { const datasets = ctx.chart.data.datasets; const count = datasets[0].data.length; let max = 0; for (let i = 0; i < count; i++) { let sum = 0; for (const dataset of datasets) { sum += dataset.data[i]; } max = Math.max(max, sum); } return max; }

function minValue(ctx) {
  const dataset = ctx.chart.data.datasets[0];
  const min = dataset.data.reduce((max, point) => Math.min(point, max), Infinity);
  return isFinite(min) ? min : 0;
}
function maxValue(ctx) {
  const datasets = ctx.chart.data.datasets;
  const count = datasets[0].data.length;
  let max = 0;
  for (let i = 0; i < count; i++) {
    let sum = 0;
    for (const dataset of datasets) {
      sum += dataset.data[i];
    }
    max = Math.max(max, sum);
  }
  return max;
}

const DATA_COUNT = 8; const MIN = 10; const MAX = 100; Utils.srand(8); const labels = []; for (let i = 0; i < DATA_COUNT; ++i) { labels.push('' + i); } const numberCfg = {count: DATA_COUNT, min: MIN, max: MAX}; const data = { labels: labels, datasets: [{ data: Utils.numbers(numberCfg) }, { data: Utils.numbers(numberCfg) }, { data: Utils.numbers(numberCfg) }] };

const DATA_COUNT = 8;
const MIN = 10;
const MAX = 100;
Utils.srand(8);
const labels = [];
for (let i = 0; i < DATA_COUNT; ++i) {
  labels.push('' + i);
}
const numberCfg = {count: DATA_COUNT, min: MIN, max: MAX};
const data = {
  labels: labels,
  datasets: [{
    data: Utils.numbers(numberCfg)
  }, {
    data: Utils.numbers(numberCfg)
  }, {
    data: Utils.numbers(numberCfg)
  }]
};