0๐
@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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Source:stackexchange.com