How can I add the sum of all values as chart title for a doughnut chart in Chart.Js?

Question

My example currently looks like this:

var ctx = document.getElementById("myChart");
var myChart = new Chart(ctx, {
    type: 'doughnut',
    data: {
        labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
        datasets: [{
            label: '# of Votes',
            data: [12, 19, 3, 5, 2, 3],
            backgroundColor: [
                'rgba(255, 99, 132, 0.2)',
                'rgba(54, 162, 235, 0.2)',
                'rgba(255, 206, 86, 0.2)',
                'rgba(75, 192, 192, 0.2)',
                'rgba(153, 102, 255, 0.2)',
                'rgba(255, 159, 64, 0.2)'
            ],
            borderColor: [
                'rgba(255,99,132,1)',
                'rgba(54, 162, 235, 1)',
                'rgba(255, 206, 86, 1)',
                'rgba(75, 192, 192, 1)',
                'rgba(153, 102, 255, 1)',
                'rgba(255, 159, 64, 1)'
            ],
            borderWidth: 1
        }]
    },
    options: {
        rotation: 1 * Math.PI,
        circumference: 1 * Math.PI,
        title: {
           display: true,
           text: 'Custom Chart Title',
           position: 'bottom'
        }
     }
});

Now I want to display the sum of the values from data: [12, 19, 3, 5, 2, 3] as title of the chart (So, in this case the title would be 44). Some example fiddle is here: https://jsfiddle.net/ktq8mb0z/. How can I achieve that in Chart.Js?

Answer 1

Since ChartJS version 3.x.x:

• half-doughnut is configured with degrees
• title is part of 'plugins'

Therefore, use this configuration:

options: {
  rotation: -90,
  circumference: 180,
    plugins: {
      title: {
        display: true,
        text: 'Total: ' + data.reduce((total, dataPoint) => total + dataPoint, 0),
        position: 'bottom',
      },
    },
}

Answer 2

You can user reduce function

dataset[0].data.reduce((x,y)=>x+y)

or You can also use this

dataset.reduce((t,d) => t + d.data.reduce((a,b) => a+b),0)

var ctx = document.getElementById("myChart");

var dataset=[{
            label: '# of Votes',
            data: [12, 19, 3, 5, 2, 3],
            backgroundColor: [
                'rgba(255, 99, 132, 0.2)',
                'rgba(54, 162, 235, 0.2)',
                'rgba(255, 206, 86, 0.2)',
                'rgba(75, 192, 192, 0.2)',
                'rgba(153, 102, 255, 0.2)',
                'rgba(255, 159, 64, 0.2)'
            ],
            borderColor: [
                'rgba(255,99,132,1)',
                'rgba(54, 162, 235, 1)',
                'rgba(255, 206, 86, 1)',
                'rgba(75, 192, 192, 1)',
                'rgba(153, 102, 255, 1)',
                'rgba(255, 159, 64, 1)'
            ],
            borderWidth: 1
        }];
var myChart = new Chart(ctx, {
    type: 'doughnut',
    data: {
        labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
        datasets: dataset
    },
    options: {
        rotation: 1 * Math.PI,
        circumference: 1 * Math.PI,
        title: {
           display: true,
           text: 'Custom Chart Title and Sum is : '+dataset.reduce((t,d) => t + d.data.reduce((a,b) => a+b),0),
           position: 'bottom'
        }
     }
});

.snippet-code .snippet-result .snippet-result-code{
    min-height:640px!important;
    height:640px!important;
}

<script src="https://cdn.jsdelivr.net/npm/chart.js@2.8.0"></script>
<canvas id="myChart" width="400" height="400"></canvas>