柱图正负值显示不同颜色

function main(chartView) {
    var chart = chartView.getChartObject();
    var options = chart.getOptions();
    var series = options.series;
    var datas = [];
    for (var i in series) {
        if (series[i].type == "bar") {
            debugger;
            datas = series[i].data;
        }
    }
    for (var i in datas) {
        if (parseInt(datas[i].displayValue) < 0) {
            datas[i].itemStyle = datas[i].itemStyle || {};
            datas[i].itemStyle = {
                    "normal": {
                        "color": "#99CC33"
                    }
                }
                //设置小于0的柱图的颜色
        }
    }
}