How to Add Grouped Bar Charts with Chart.js?

To add grouped bar charts with Chart.js, we just have to put all the chart data in the datasets array property.

For instance, we can add the Chart.js script and the canvas for the chart with the following HTML:

<script src="https://cdn.jsdelivr.net/npm/chart.js"></script>
<canvas id="myChart"></canvas>

Then we write:

const ctx = document.getElementById('myChart').getContext('2d');
const data = {
  labels: ["Chocolate", "Vanilla", "Strawberry"],
  datasets: [{
      label: "Blue",
      backgroundColor: "blue",
      data: [3, 7, 4]
    },
    {
      label: "Red",
      backgroundColor: "red",
      data: [4, 3, 5]
    },
    {
      label: "Green",
      backgroundColor: "green",
      data: [7, 2, 6]
    }
  ]
};

const myBarChart = new Chart(ctx, {
  type: 'bar',
  data: data,
  options: {
    barValueSpacing: 20,
    scales: {
      yAxes: [{
        ticks: {
          min: 0,
        }
      }]
    }
  }
});

to get the canvas 2d context with:

const ctx = document.getElementById('myChart').getContext('2d');

Then chart data is defined with:

const data = {
  labels: ["Chocolate", "Vanilla", "Strawberry"],
  datasets: [{
      label: "Blue",
      backgroundColor: "blue",
      data: [3, 7, 4]
    },
    {
      label: "Red",
      backgroundColor: "red",
      data: [4, 3, 5]
    },
    {
      label: "Green",
      backgroundColor: "green",
      data: [7, 2, 6]
    }
  ]
};

Each entry has the data for each bar.

They’ll be grouped together into a group bar chart with Chart.js.

Then we create our chart with:

const myBarChart = new Chart(ctx, {
  type: 'bar',
  data: data,
  options: {
    barValueSpacing: 20,
    scales: {
      yAxes: [{
        ticks: {
          min: 0,
        }
      }]
    }
  }
});

We just set type to 'bar' to create a grouped bar chart.