class-12.md

Chart.js

It's easy to get started with Chart.js. All that's required is the script included in your page along with a single <canvas> node to render the chart.

Getting Started

Let's get started using Chart.js!

1. First, we need to have a canvas in our page.

<canvas id="myChart" width="400" height="400"></canvas>

2. Now that we have a canvas we can use, we need to include Chart.js in our page.

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

3. Now, we can create a chart. We add a script to our page.

    var ctx = document.getElementById('myChart').getContext('2d');
    var myChart = new Chart(ctx, {
        type: 'bar',
        data: {
    labels: ['Red', 'Blue', 'Yellow'],
    datasets: [{
        label: '# of Votes',
        data: [12, 19, 3, 5, 2, 3],
        backgroundColor: [
            'rgba(255, 99, 132, 0.2)',
        ],
        borderColor: [
            'rgba(255, 99, 132, 1)',
        ],
        borderWidth: 1
    }]
    },
    options: {
    scales: {
        y: {
            beginAtZero: true
        }
    }
    }
    });
   

The <canvas> element

At first sight a <canvas> looks like the <img> element, with the only clear difference being that it doesn't have the src and alt attributes. Indeed, the <canvas> element has only two attributes, width and height.

The <canvas> element creates a fixed-size drawing surface that exposes one or more rendering contexts, which are used to create and manipulate the content shown. In this tutorial, we focus on the 2D rendering context.