I am using chart.js to develop a TreeMap. It works great but the issue is each rectangle only shows the value of the data. I want to add some custom text next to the value. How do I achieve this?
var topTags = [
{tag:'python',num:133269},{tag:'javascript',num:109742},{tag:'java',num:65490},{tag:'c#',num:45445},{tag:'html',num:43767},{tag:'android',num:42657},{tag:'reactjs',num:38844},{tag:'php',num:34381},{tag:'sql',num:29996},{tag:'python',num:29942},{tag:'css',num:29654},{tag:'r',num:28319},{tag:'c++',num:27389},{tag:'node.js',num:25415},{tag:'angular',num:24093},{tag:'pandas',num:23826},{tag:'arrays',num:23075},{tag:'jquery',num:18968},{tag:'mysql',num:18863},{tag:'swift',num:17971},{tag:'ios',num:17600},{tag:'json',num:15589},{tag:'laravel',num:15537},{tag:'flutter',num:15201},{tag:'c',num:15195},{tag:'django',num:14748},{tag:'sql',num:12752},{tag:'reactjs',num:10974},{tag:'excel',num:10962},{tag:'list',num:10726},{tag:'regex',num:10676}
];
var canvas = document.getElementById("treemap");
var ctx = canvas.getContext("2d");
var chart = window.chart = new Chart(ctx, {
type: "treemap",
data: {
datasets: [{
tree: topTags,
key: "num",
groups: ['num'],
spacing: 0.5,
borderWidth: 1.5,
fontColor: "black",
borderColor: "grey"
}]
},
options: {
maintainAspectRatio: false,
legend: { display: false },
tooltips: { enabled: false }
}
});
When running this code, I get the numbers in each rectangle but I need some text to be appended next to the numbers for each rectangle. How do I achieve this?
You can use the formatter options in the labels section:
const options = {
type: 'treemap',
data: {
datasets: [{
label: '# of Votes',
tree: [12, 19, 3, 5, 2, 3],
backgroundColor: 'pink',
labels: {
display: true,
formatter(ctx) {
const data = ctx.chart.data;
return `Custom Text: ${data.datasets[ctx.datasetIndex].tree[ctx.dataIndex]}`;
}
},
}]
},
options: {}
}
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/3.7.0/chart.js"></script>
<script src="https://cdn.jsdelivr.net/npm/chartjs-chart-treemap@2.0.1/dist/chartjs-chart-treemap.js"></script>
</body>