如何在Chart.js中更改y轴标签的不同颜色

var ctx = document.getElementById('myChart').getContext('2d');
var 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(0, 0, 0, 0.1)',
            borderColor: 'rgba(0, 0, 0, 1)',
            borderWidth: 1
        }]
    },
    options: {
        scales: {
            y: {
                ticks: {
                    callback: function(value, index, values) {
                        if (value === 5) {
                            return {
                                value: value,
                                font: {
                                    weight: 'bold',
                                    color: 'red'
                                }
                            };
                        } else if (value === 10) {
                            return {
                                value: value,
                                font: {
                                    weight: 'bold',
                                    color: 'blue'
                                }
                            };
                        } else {
                            return value;
                        }
                    }
                }
            }
        }
    }
});