Highcharts Uncaught TypeError: Cannot set property 'day' of undefined

Highcharts Uncaught TypeError: Cannot set property 'day' of undefined

我有一个 highcharts 图表,我正在尝试使用以下方法在点击事件上手动设置 x 轴标签格式:

stockchart.xAxis[0].dateTimeLabelFormats.day = "%b %e";

但是,我收到 "Uncaught TypeError: Cannot set property 'day' of undefined"。谁能解释我做错了什么?

所以,由于 Pawel 的建议,这对我有用:

stockchart.xAxis[0].update({
            dateTimeLabelFormats: {
                day: "%b %e"
            }
        });