Chart.js 动态图表的使用

一、相关资料

1. 简介

Chart.js 是一个基于 HTML5 的简单的面向对象的图表库,支持包括 IE7/8 和所有现代浏览器。支持六种图标:曲线图(Linecharts)、柱状图(Barcharts)、雷达图(Radarcharts)、饼状图(Piecharts)、极坐标区域图(Polararea charts)以及圆环图(Doughnutcharts)。并且带有动画效果(animated),支持 retina 屏。

2. 官网

官网:https://www.chartjs.org/

二、示例代码

本案例演示了最近 24 小时的 PV/UV 实时数据,在线 DEMO

<!DOCTYPE html>
<html>
<head>
    <title>Chart.js 动态图表的使用</title>
    <script src="https://cdn.jsdelivr.net/npm/chart.js@2.8.0"></script>
</head>
<body>
    <div>
        <canvas id="chart"></canvas>
    </div>

    <script type="text/javascript">
    
        var dataLabels = ['1h', '2h', '3h', '4h', '5h', '6h', '7h', '8h', '9h', '10h', '11h', '12h', '13h', '14h', '15h', '16h', '17h', '18h', '19h', '20h', '21h', '22h', '23h', '0h'];
        var dataPV = [133058,253219,255194,233058,253219,277318,277714,273337,255194,277318,277714,273337,233058,253219,277318,253219,277318,277714,273337,255194,277714,273337,255194,293058];
        var dataUV = [10651,22039,23955,23754,22664,10651,22039,23765,23955,23754,22664,23765,23955,23754,22664,10651,22039,23765,10651,22039,23765,23955,23754,22664];

        var config = {
            type: 'line',
            data: {
                labels: dataLabels,
                datasets: [
                    {
                        label: 'PV',
                        data: dataPV,
                        backgroundColor: 'rgb(255, 99, 132)',
                        borderColor: 'rgb(255, 99, 132)',
                        fill: false,
                    },
                    {
                        label: 'UV',
                        data: dataUV, 
                        backgroundColor: 'rgb(75, 192, 192)',
                        borderColor: 'rgb(75, 192, 192)',
                        fill: false, 
                    }
                ]
            },
            options: {
                responsive: true,
                title: {
                    display: true,
                    text: 'PV/UV 实时统计'
                },
            }
        };

        var ctx = document.getElementById('chart').getContext('2d');
        var chart = new Chart(ctx, config);

        setInterval(function() {
            if (config.data.datasets.length > 0) {

                var last = parseInt(dataLabels[dataLabels.length - 1]);
                var label = last + 1;
                if (last >= 23) {
                    label = 0;
                }
                label = label + 'h';

                dataLabels.push(label);
                dataPV.push(getRandomNum(200000, 300000));
                dataUV.push(getRandomNum(10000, 80000));

                dataLabels.shift();
                dataPV.shift();
                dataUV.shift();

                chart.update();
            }
        }, 1000);

        function getRandomNum(min, max) {
            var range = max - min;
            var rand = Math.random();
            return(min + Math.round(rand * range));
        }

    </script>
</body>
</html>

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