Average

const config = { type: 'line', data, options: { plugins: { annotation: { annotations: { annotation } } } } };

const config = {
  type: 'line',
  data,
  options: {
    plugins: {
      annotation: {
        annotations: {
          annotation
        }
      }
    }
  }
};

const annotation = { type: 'line', borderColor: 'black', borderDash: [6, 6], borderDashOffset: 0, borderWidth: 3, label: { enabled: true, content: (ctx) => 'Average: ' + average(ctx).toFixed(2), position: 'end' }, scaleID: 'y', value: (ctx) => average(ctx) };

const annotation = {
  type: 'line',
  borderColor: 'black',
  borderDash: [6, 6],
  borderDashOffset: 0,
  borderWidth: 3,
  label: {
    enabled: true,
    content: (ctx) => 'Average: ' + average(ctx).toFixed(2),
    position: 'end'
  },
  scaleID: 'y',
  value: (ctx) => average(ctx)
};

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) }] };

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)
  }]
};

function average(ctx) { const values = ctx.chart.data.datasets[0].data; return values.reduce((a, b) => a + b, 0) / values.length; }

function average(ctx) {
  const values = ctx.chart.data.datasets[0].data;
  return values.reduce((a, b) => a + b, 0) / values.length;
}