(Please note: There are lots of answers for v2, this is for v3)
I'm trying to setup tooltips label and title for a doughnut chart.
Code:
//Create the donut chart
donut = new Chart('questions_positivity_donut', {
type: 'doughnut',
data: {
labels: ["Positive", "Other"],
datasets: [{
label: 'Sentiment',
data: [user_context.state.avg_joy, (1-user_context.state.avg_joy)],
backgroundColor: ['#a9a9a9','#f2f2f2']
}]
},
options: {
cutout: "70%",
plugins: {
legend: {
display: false
},
maintainAspectRatio: false,
responsive: true,
tooltip: {
callbacks: {
label: function(context) {
let label = new Intl.NumberFormat('en-US', {style: 'percent', minimumFractionDigits: 0, maximumFractionDigits: 0}).format(context.formattedValue);
return label;
},
title: function(context) {
let title = context.parsed.x;
return title;
}
},
displayColors: false
}
}
}
});
The label now works, and displays the value of the data, but the title is returning blank, instead of returning the label of the data ("Positive" or "Other").
How can I return the correct title in the tooltip.callback?
Example: "Positive 35%" and "Other 65%"
If you log the context you could see its an array containing objects, with the default interaction mode you are using it only contains a single item so you can select that one and then access the label attribute on it like so:
var options = {
type: 'doughnut',
data: {
labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
backgroundColor: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"]
}]
},
options: {
plugins: {
tooltip: {
callbacks: {
label: function(context) {
let label = new Intl.NumberFormat('en-US', {
style: 'percent',
minimumFractionDigits: 0,
maximumFractionDigits: 0
}).format(context.formattedValue);
return label;
},
title: function(context) {
let title = context[0].label;
return title;
}
},
}
}
}
}
var 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>
</body>