This sample shows how to use the external tooltip functionality to generate an HTML tooltip.
const config = {
type: 'line',
data: data,
options: {
interaction: {
mode: 'index',
intersect: false,
},
plugins: {
title: {
display: true,
text: 'Chart.js Line Chart - External Tooltips'
},
tooltip: {
enabled: false,
position: 'nearest',
external: externalTooltipHandler
}
}
}
};
const DATA_COUNT = 7;
const NUMBER_CFG = {count: DATA_COUNT, min: -100, max: 100, decimals: 0};
const data = {
labels: Utils.months({count: DATA_COUNT}),
datasets: [
{
label: 'Dataset 1',
data: Utils.numbers(NUMBER_CFG),
fill: false,
borderColor: Utils.CHART_COLORS.red,
backgroundColor: Utils.transparentize(Utils.CHART_COLORS.red, 0.5),
},
{
label: 'Dataset 2',
data: Utils.numbers(NUMBER_CFG),
fill: false,
borderColor: Utils.CHART_COLORS.blue,
backgroundColor: Utils.transparentize(Utils.CHART_COLORS.blue, 0.5),
},
]
};
const getOrCreateTooltip = (chart) => {
let tooltipEl = chart.canvas.parentNode.querySelector('div');
if (!tooltipEl) {
tooltipEl = document.createElement('div');
tooltipEl.style.background = 'rgba(0, 0, 0, 0.7)';
tooltipEl.style.borderRadius = '3px';
tooltipEl.style.color = 'white';
tooltipEl.style.opacity = 1;
tooltipEl.style.pointerEvents = 'none';
tooltipEl.style.position = 'absolute';
tooltipEl.style.transform = 'translate(-50%, 0)';
tooltipEl.style.transition = 'all .1s ease';
const table = document.createElement('table');
table.style.margin = '0px';
tooltipEl.appendChild(table);
chart.canvas.parentNode.appendChild(tooltipEl);
}
return tooltipEl;
};
const externalTooltipHandler = (context) => {
const {chart, tooltip} = context;
const tooltipEl = getOrCreateTooltip(chart);
if (tooltip.opacity === 0) {
tooltipEl.style.opacity = 0;
return;
}
if (tooltip.body) {
const titleLines = tooltip.title || [];
const bodyLines = tooltip.body.map(b => b.lines);
const tableHead = document.createElement('thead');
titleLines.forEach(title => {
const tr = document.createElement('tr');
tr.style.borderWidth = 0;
const th = document.createElement('th');
th.style.borderWidth = 0;
const text = document.createTextNode(title);
th.appendChild(text);
tr.appendChild(th);
tableHead.appendChild(tr);
});
const tableBody = document.createElement('tbody');
bodyLines.forEach((body, i) => {
const colors = tooltip.labelColors[i];
const span = document.createElement('span');
span.style.background = colors.backgroundColor;
span.style.borderColor = colors.borderColor;
span.style.borderWidth = '2px';
span.style.marginRight = '10px';
span.style.height = '10px';
span.style.width = '10px';
span.style.display = 'inline-block';
const tr = document.createElement('tr');
tr.style.backgroundColor = 'inherit';
tr.style.borderWidth = 0;
const td = document.createElement('td');
td.style.borderWidth = 0;
const text = document.createTextNode(body);
td.appendChild(span);
td.appendChild(text);
tr.appendChild(td);
tableBody.appendChild(tr);
});
const tableRoot = tooltipEl.querySelector('table');
while (tableRoot.firstChild) {
tableRoot.firstChild.remove();
}
tableRoot.appendChild(tableHead);
tableRoot.appendChild(tableBody);
}
const {offsetLeft: positionX, offsetTop: positionY} = chart.canvas;
tooltipEl.style.opacity = 1;
tooltipEl.style.left = positionX + tooltip.caretX + 'px';
tooltipEl.style.top = positionY + tooltip.caretY + 'px';
tooltipEl.style.font = tooltip.options.bodyFont.string;
tooltipEl.style.padding = tooltip.options.padding + 'px ' + tooltip.options.padding + 'px';
};
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