1、柱状渐变

渐变

    itemStyle: {
                normal: {
                    color: new echarts.graphic.LinearGradient(
                        0, 0, 0, 1,
                        [
                            {offset: 0, color: '#83bff6'},
                            {offset: 0.5, color: '#fff'},
                            {offset: 1, color: '#188df0'}
                        ]
                    )
                }
            }