Chartjs-Catch event of show and hide dataset at chart.js

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You can make use of the legend onClick handler like so:

const defaultLegendClickHandler = Chart.defaults.plugins.legend.onClick;
const pieDoughnutLegendClickHandler = Chart.controllers.doughnut.overrides.plugins.legend.onClick;

const options = {
  type: 'line',
  data: {
    labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
    datasets: [{
        label: 'Strength',
        data: [12, 19, 3, 5, 2, 3],
        borderColor: 'pink'
      },
      {
        label: 'Avg data, %',
        data: [7, 11, 5, 8, 3, 7],
        borderColor: 'orange'
      }
    ]
  },
  options: {
    plugins: {
      legend: {
        onClick: (evt, legendItem, legend) => {
          const type = legend.chart.config.type;

          if (type === 'pie' || type === 'doughnut') {
            pieDoughnutLegendClickHandler(evt, legendItem, legend)
          } else {
            defaultLegendClickHandler(evt, legendItem, legend);
          }

          if (legendItem.text !== 'Strength') {
            return;
          }

          legend.chart.options.plugins.annotation.annotations.line1.display = !legend.chart.getDatasetMeta(0).hidden;
          legend.chart.update();
        }
      },
      annotation: {
        annotations: {
          line1: {
            type: 'line',
            yMin: 4,
            yMax: 6,
            borderColor: 'rgba(234,6,6,0.7)',
            borderWidth: 1,
            borderDash: [2, 2],
            display: true
          }
        }
      }
    }
  }
}

const ctx = document.getElementById('chartJSContainer').getContext('2d');
new Chart(ctx, options);
<body>
  <canvas id="chartJSContainer" width="600" height="400"></canvas>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.5.1/chart.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/chartjs-plugin-annotation/1.0.2/chartjs-plugin-annotation.js"></script>
</body>

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