使用chart.js时条形图的不同颜色

var ctx = document.getElementById('myChart').getContext('2d');
var myChart = new Chart(ctx, {
    type: 'bar',
    data: {
        labels: ['Red', 'Blue', 'Yellow', 'Green', 'Purple', 'Orange'],
        datasets: [{
            label: 'My Dataset',
            data: [12, 19, 3, 5, 2, 3],
            backgroundColor: ['red', 'blue', 'yellow', 'green', 'purple', 'orange']
        }]
    },
    options: {
        // 配置选项
    }
});

var ctx = document.getElementById('myChart').getContext('2d');
var myChart = new Chart(ctx, {
    type: 'bar',
    data: {
        labels: ['Red', 'Blue', 'Yellow', 'Green', 'Purple', 'Orange'],
        datasets: [{
            label: 'My Dataset',
            data: [12, 19, 3, 5, 2, 3],
            backgroundColor: function(context) {
                var value = context.dataset.data[context.dataIndex];
                if (value > 10) {
                    return 'green';
                } else {
                    return 'red';
                }
            }
        }]
    },
    options: {
        // 配置选项
    }
});