ECharts series data 数组里面的元素，可以是对象

修改自：https://echarts.apache.org/examples/zh/editor.html?c=line-stack

注意：

1. 对象里面value的值，用来显示在y轴上。

option = {
    title: {
        text: '折线图堆叠'
    },
    tooltip: {
        trigger: 'axis',
        formatter: p => {
            let returnStr = ''
            let len = p.length
            for (let i = 0; i< len; i++) {
                returnStr += 'name:' + String(p[i].name) + 
                ', value:' + String(p[i].value) + ' <br/>'
            }
            return returnStr
        }
    },
    legend: {
        data: ['邮件营销', '联盟广告', '视频广告', '直接访问', '搜索引擎']
    },
    grid: {
        left: '3%',
        right: '4%',
        bottom: '3%',
        containLabel: true
    },
    toolbox: {
        feature: {
            saveAsImage: {}
        }
    },
    xAxis: {
        type: 'category',
        boundaryGap: false,
        data: ['周一', '周二', '周三', '周四', '周五', '周六', '周日']
    },
    yAxis: {
        type: 'value'
    },
    series: [
        {
            name: '邮件营销',
            type: 'line',
            stack: '总量',
            data: [
                {'name':'jeff','age':18,'value':18}, 
                {'name':'jeff','age':18,'value':118}
            ]
        },
        {
            name: '联盟广告',
            type: 'line',
            stack: '总量',
            data: [
                {'name':'jeff','age':18,'value':19}, 
                {'name':'jeff','age':18,'value':219}
            ]
        },
        {
            name: '视频广告',
            type: 'line',
            stack: '总量',
            data: [
                {'name':'jeff','age':18,'value':20}, 
                {'name':'jeff','age':18,'value':320}
            ]
        },
        {
            name: '直接访问',
            type: 'line',
            stack: '总量',
            data: [
                {'name':'jeff','age':18,'value':21},
                {'name':'jeff','age':18,'value':421}
            ]
        }
    ]
};