reading-notes

Chart.js

Reference

• Drawing Shapes with Canvas
• Applying Style and Colors - Canvas API
• Drawing Text - Canvas API

Reading

• Chart.js Documentation
• Easily Create Stunning Animated Charts with Chart.js

Notes

• Using Chart.js only requires the necessary script run along with a single <canvas> node to render the chart
• Chart.js needs to be linked in the HTML file using the following:

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

• This allows us to access the Chart.js scripting language

Use

• Always starts with a <canvas> tag:

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

• You can then use getElementById to grab the <canvas> element from the DOM:

// Any of the following formats may be used
const ctx = document.getElementById('myChart');
const ctx = document.getElementById('myChart').getContext('2d');
const ctx = $('#myChart');
const ctx = 'myChart';

• Full Example:

<canvas id="myChart" width="400" height="400"></canvas>
<script>
const ctx = document.getElementById('myChart');
const myChart = new Chart(ctx, {
    type: 'bar',
    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: {
        scales: {
            y: {
                beginAtZero: true
            }
        }
    }
});
</script>