samples/pie.html

<!doctype html>
<html>

<head>
	<title>Pie Chart</title>
	<script src="../node_modules/chart.js/dist/chart.js"></script>
	<script src="../dist/chartjs-plugin-annotation.js"></script>
	<script src="https://chartjs.org/samples/master/utils.js"></script>
</head>

<body>
	<div id="canvas-holder" style="width:40%">
		<canvas id="chart-area"></canvas>
	</div>
	<button id="randomizeData">Randomize Data</button>
	<button id="addDataset">Add Dataset</button>
	<button id="removeDataset">Remove Dataset</button>
	<script>
		const randomScalingFactor = function() {
			return Math.round(Math.random() * 100);
		};

		const config = {
			type: 'pie',
			data: {
				datasets: [{
					data: [
						randomScalingFactor(),
						randomScalingFactor(),
						randomScalingFactor(),
						randomScalingFactor(),
						randomScalingFactor(),
					],
					backgroundColor: [
						window.chartColors.red,
						window.chartColors.orange,
						window.chartColors.yellow,
						window.chartColors.green,
						window.chartColors.blue,
					],
					label: 'Dataset 1'
				}],
				labels: [
					'Red',
					'Orange',
					'Yellow',
					'Green',
					'Blue'
				]
			},
			options: {
				responsive: true,
				plugins: {
					annotation: { // not supported, and should not display or error
						drawTime: 'beforeDatasetsDraw',
						annotations: {
							myBox: {
								type: 'box',
								xScaleID: 'x',
								yScaleID: 'y',
								xMin: -120,
								xMax: 20,
								yMin: -120,
								yMax: 20,
								backgroundColor: 'rgba(101, 33, 171, 1.0)',
								borderColor: 'rgb(101, 33, 171)',
								borderWidth: 1,
								dblclick(context) {
									console.log(context.element.options.id, context);
								}
							}
						}
					}
				}
			}
		};

		window.onload = function() {
			const ctx = document.getElementById('chart-area').getContext('2d');
			window.myPie = new Chart(ctx, config);
		};

		document.getElementById('randomizeData').addEventListener('click', () => {
			config.data.datasets.forEach((dataset) => {
				dataset.data = dataset.data.map(() => randomScalingFactor());
			});

			window.myPie.update();
		});

		const colorNames = Object.keys(window.chartColors);
		document.getElementById('addDataset').addEventListener('click', () => {
			const newDataset = {
				backgroundColor: [],
				data: [],
				label: 'New dataset ' + config.data.datasets.length,
			};

			for (let index = 0; index < config.data.labels.length; ++index) {
				newDataset.data.push(randomScalingFactor());

				const colorName = colorNames[index % colorNames.length];
				const newColor = window.chartColors[colorName];
				newDataset.backgroundColor.push(newColor);
			}

			config.data.datasets.push(newDataset);
			window.myPie.update();
		});

		document.getElementById('removeDataset').addEventListener('click', () => {
			config.data.datasets.splice(0, 1);
			window.myPie.update();
		});
	</script>
</body>

</html>