图表初始化itemStyle样式echarts 折线配置项内容和展示

如何设置图表最后一个数据的itemStyle样式显示，点击不同数据点时图上白色的圆点可切换

      option = {
            grid: {
                left: '0%',
                right: '4%',
                bottom: '3%',
                containLabel: true
            },
            xAxis: {
                type: 'category',
                boundaryGap: true,
                data: ['15', '16', '17', '18', '19', '20', '21', '22','23', '24', '25', '27', '今天'],
                axisTick: {
                    show: false
                },
            },
            yAxis: {
                type: 'value',
                nameLocation: 'start',
                axisTick: {
                    show: false
                },
                axisLine: {
                    show: false
                },
                axisLabel: {
                    textStyle: {
                        color: '#fff',
                        baseline: 'bottom'
                    }
                }
            },
            series: [{
                name: '邮件营销',
                type: 'line',
                lineStyle: {
                    normal: {
                        color: 'transparent'
                    }
                },
                itemStyle: {
                    normal: {
                        areaStyle: {
                            color: (function() {
                                return {
                                    type: 'linear',
                                    x: 0,
                                    y: 0,
                                    x2: 0,
                                    y2: 1,
                                    colorStops: [{
                                        offset: 0,
                                        color: 'rgba(255,255,255,1)' // 0% 处的颜色
                                    }, {
                                        offset: 1,
                                        color: 'rgba(255,255,255,.3)' // 100% 处的颜色
                                    }],
                                    globalCoord: false // 缺省为 false
                                };
                            })()
                        },
                        borderWidth: 20,
                        opacity: 1,
                        borderColor: 'transparent',
                        color:'red'
                    },
                    emphasis: {
                        color: '#fff',
                        borderWidth: 13,
                        opacity: 1,
                        borderColor: (function() {
                            return {
                                type: 'linear',
                                x: 0,
                                y: 0,
                                x2: 0,
                                y2: 1,
                                colorStops: [{
                                    offset: 0,
                                    color: 'rgba(255,255,255,1)' // 0% 处的颜色
                                }, {
                                    offset: 1,
                                    color: 'rgba(255,255,255,.3)' // 100% 处的颜色
                                }],
                                globalCoord: false // 缺省为 false
                            };
                        })()
                    }
                },
                data: [67, 68, 69, 78, 70, 77, 89, 88, 78, 90, 67, 90, {value:87,
            symbol:'pin',
            symbolSize:20}]
            }],
            backgroundColor: {
                type: 'linear',
                x: 0,
                y: 0,
                x2: 1,
                y2: 0,
                colorStops: [{
                    offset: 0,
                    color: 'rgb(248,93,75)' // 0% 处的颜色
                }, {
                    offset: 1,
                    color: 'rgb(253,134,52)' // 100% 处的颜色
                }],
                globalCoord: false // 缺省为 false
            }
        };
        myChart.on('click', function (params) {
//          alert(params.name);
            
            for (var i = 0; i < option.series[0].data.length; i++) {
                
                if ((typeof  option.series[0].data[i]) !== 'number') {
                    option.series[0].data[i] = option.series[0].data[i].value;
                }
                if (params.name == option.xAxis.data[i]) {
//                        console.log(typeof option.series[0].data[i]);
                    if ((typeof option.series[0].data[i]) == 'number') {
                        option.series[0].data[i] = {
                            value: params.value,
                            symbol: 'pin',
                            symbolSize: 20
                        };
                    }
                }
            }
            myChart.clear();
            myChart.setOption(option);
        });