Chart JS:旧图表数据未清除

// 假设你有一个 id 为 'myChart' 的图表容器
var ctx = document.getElementById('myChart').getContext('2d');

// 创建图表实例
var myChart = new Chart(ctx, {
    type: 'line',
    data: {
        labels: ['January', 'February', 'March', 'April', 'May', 'June', 'July'],
        datasets: [{
            label: 'My First dataset',
            backgroundColor: 'rgb(255, 99, 132)',
            borderColor: 'rgb(255, 99, 132)',
            data: [0, 10, 5, 2, 20, 30, 45]
        }]
    },
    options: {}
});

// 更新图表数据
function updateChart(newData) {
    // 销毁旧图表实例
    if (myChart) {
        myChart.destroy();
    }

    // 创建新图表实例
    myChart = new Chart(ctx, {
        type: 'line',
        data: {
            labels: newData.labels,
            datasets: [{
                label: 'My First dataset',
                backgroundColor: 'rgb(255, 99, 132)',
                borderColor: 'rgb(255, 99, 132)',
                data: newData.data
            }]
        },
        options: {}
    });
}

// 示例：更新图表数据
var newData = {
    labels: ['August', 'September', 'October', 'November', 'December'],
    data: [50, 60, 70, 80, 90]
};
updateChart(newData);