echart 图表月份不足 前端开发用0补足

<template>
    <div>
      <div id="Echart_chartId"></div>
    </div>
</template>

<script>
export default {
  name: 'Echart',
  data () {
    return {
      xdata: [],
      ydata: []
    }
  },
  mounted () {
    this.getDats()
    this.initChart()
  },
  methods: {
    getDats () {
      const xdata = []
      const ydata = []
      const monthas = [
        {'val': 121, 'month': 3},
        {'val': 19, 'month': 4},
        {'val': 21, 'month': 7},
        {'val': 31, 'month': 8},
        {'val': 51, 'month': 10},
        {'val': 21, 'month': 11},
        {'val': 91, 'month': 12}
      ]
      const monthMap = []
      monthas.forEach(item => {
        const cur = item.month
        monthMap[cur] = item
      })

      for (let i = 1; i < 13; i++) {
        let month = '' + i
        if (i < 10) {
          month = '0' + i
        }
        xdata.push(month)
        const val = monthMap[i]
        if (val) {
          ydata.push(val.val)
        } else {
          ydata.push(0)
        }
      }
      this.xdata = xdata
      this.ydata = ydata
    },
    initChart () {
      const chart = this.$echarts.init(document.getElementById('Echart_chartId')) // 我全局引入的echarts
      chart.setOption({
        tooltip: {
          trigger: 'axis',
          axisPointer: {
            type: 'cross'
          }
        },
        legend: {
          data: [ '月份' ],
          left: '6%'
        },
        grid: {
          left: '3%',
          right: '3%',
          top: '3%',
          bottom: '3%'
        },
        xAxis: {
          type: 'category',
          data: this.xdata,
          splitLine: {
            show: false
          },
          boundaryGap: false
        },
        yAxis: {
          type: 'value',
          splitLine: {
            show: false
          },
        },
        series: [
          {
            type: 'line',
            name: '月份',
            data: this.ydata
          }
        ]
      })
    }
  }
}
</script>

<style scoped>
#Echart_chartId{
  height: 270px;
   60%;
}
</style>