向yAxes Chart.js添加多行labelString

<canvas id="myChart"></canvas>

var ctx = document.getElementById('myChart').getContext('2d');
var myChart = new Chart(ctx, {
    type: 'line',
    data: {
        labels: ['January', 'February', 'March', 'April', 'May', 'June', 'July'],
        datasets: [{
            label: 'Dataset 1',
            data: [10, 20, 30, 40, 50, 60, 70],
            borderColor: 'red',
            fill: false
        }, {
            label: 'Dataset 2',
            data: [20, 30, 40, 50, 60, 70, 80],
            borderColor: 'blue',
            fill: false
        }]
    },
    options: {
        scales: {
            yAxes: [{
                ticks: {
                    beginAtZero: true
                },
                scaleLabel: {
                    display: true,
                    labelString: 'Label Line 1\nLabel Line 2'
                }
            }]
        }
    }
});