Chartjs-How can I have smaller labels with Chart.js?

0๐Ÿ‘

@user2057925 is right. You should use an HTML legend through a plugin. The code is given in Chart.js documentation and all you have to do is tweaking styles a bit (especially overflow).

Here is a full example:

const ctx = document.getElementById('myChart');

const getOrCreateLegendList = (chart, id) => {
  const legendContainer = document.getElementById(id);
  let listContainer = legendContainer.querySelector('ul');

  if (!listContainer) {
    listContainer = document.createElement('ul');
    
    // ========================= TWEAK THAT =========================
    listContainer.style.display = 'flex';
    listContainer.style.flexDirection = 'column';
    listContainer.style.margin = 'auto';
    listContainer.style.padding = 0;
    listContainer.style.width = '150px';
    listContainer.style.height = '60px';
    listContainer.style.overflow = 'scroll'; // <--- DO NOT FORGET THIS
    // ==================================================

    legendContainer.appendChild(listContainer);
  }

  return listContainer;
};

const htmlLegendPlugin = {
  id: 'htmlLegend',
  afterUpdate(chart, args, options) {
    const ul = getOrCreateLegendList(chart, options.containerID);

    // Remove old legend items
    while (ul.firstChild) {
      ul.firstChild.remove();
    }

    // Reuse the built-in legendItems generator
    const items = chart.options.plugins.legend.labels.generateLabels(chart);

    items.forEach(item => {
      const li = document.createElement('li');
      li.style.alignItems = 'center';
      li.style.cursor = 'pointer';
      li.style.display = 'flex';
      li.style.flexDirection = 'row';
      li.style.marginTop = '5px';
      li.style.marginLeft = '10px';

      li.onclick = () => {
        const {type} = chart.config;
        if (type === 'pie' || type === 'doughnut') {
          // Pie and doughnut charts only have a single dataset and visibility is per item
          chart.toggleDataVisibility(item.index);
        } else {
          chart.setDatasetVisibility(item.datasetIndex, !chart.isDatasetVisible(item.datasetIndex));
        }
        chart.update();
      };

      // Color box
      const boxSpan = document.createElement('span');
      boxSpan.style.background = item.fillStyle;
      boxSpan.style.borderColor = item.strokeStyle;
      boxSpan.style.borderWidth = item.lineWidth + 'px';
      boxSpan.style.display = 'inline-block';
      boxSpan.style.height = '20px';
      boxSpan.style.marginRight = '10px';
      boxSpan.style.width = '20px';

      // Text
      const textContainer = document.createElement('p');
      textContainer.style.color = item.fontColor;
      textContainer.style.margin = 0;
      textContainer.style.padding = 0;
      textContainer.style.textDecoration = item.hidden ? 'line-through' : '';

      const text = document.createTextNode(item.text);
      textContainer.appendChild(text);

      li.appendChild(boxSpan);
      li.appendChild(textContainer);
      ul.appendChild(li);
    });
  }
};

new Chart(ctx, {
  type: 'line',
  data: {
    labels: ['Label 1', 'Label 2', 'Label 3'],
    datasets: [{
      label: 'Dataset 1',
      data: [10, 20, 15]
    }, {
      label: 'Dataset 2',
      data: [7, 3, 11]
    }, {
      label: 'Dataset 3',
      data: [6, 8, 12]
    }]
  },
  options: {
    scales: {
      y: {
        beginAtZero: true
      }
    },
    plugins: {
      htmlLegend: {
        containerID: 'legend-container'
      },
      legend: {
        display: false
      }
    }
  },
  plugins: [htmlLegendPlugin]
});
.chart-container {
  position: relative;
  width: 500px;
}
<script src="https://cdn.jsdelivr.net/npm/chart.js"></script>

<div class="chart-container">
  <div id="legend-container"></div>
  <canvas id="myChart"></canvas>
</div>

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