element 日期选择器date-picker 设置默认月份（当年1月到当前月），结束月份大于开始月份，开始月份小于结束月份

1. 初始月份设置

先放效果图

• 月份选择器

<el-date-picker
   v-model="checkFieldFormData.fromDate"
    :picker-options="pickerOptionsStart"
    type="month"
    format="yyyy-MM"
    value-format="yyyyMM"
    placeholder="开始月份"
  >
  </el-date-picker>
  <span class="speator-date">-</span>
  <el-date-picker
    v-model="checkFieldFormData.toDate"
    :picker-options="pickerOptionsEnd"
    type="month"
    format="yyyy-MM"
    value-format="yyyyMM"
    placeholder="结束月份"
  >
  </el-date-picker>

• 在data中定义

checkFieldFormData: {
	fromDate: '',
    toDate: ''
}

• 获取默认月份

mounted() {
  this.skMonthrangeDefault()
},

skMonthrangeDefault() {
  var now = new Date()
  let month = now.getMonth() + 1
  if (month >= 1 && month <= 9) {
    month = '0' + month
  }
  var startDate = now.getFullYear() + '01' // 形式与value-format一致
  var endDate = now.getFullYear() + month.toString()
  this.$set(this.checkFieldFormData, 'fromDate', startDate)
  this.$set(this.checkFieldFormData, 'toDate', endDate)
},

注意：这里用了$set修改data数据，否则切换月份时，视图不更新。

2. 结束月份大于开始月份，开始月份小于结束月份，禁用月份设置

刚开始的时候看网上的文章好多是把pickerOptionsStart禁用选项写在data里，自己尝试做的时候一直是报错的，就把这些放在了computed中。

computed: {
   pickerOptionsStart() {
     return {
       disabledDate: time => {
         if (this.checkFieldFormData && this.checkFieldFormData.toDate) {
           const resDate = (new Date(time).getFullYear() + '-' + this.pMonth(new Date(time).getMonth() + 1)).replace(/-/g, '')
           return resDate > this.checkFieldFormData.toDate
         }
       }
     }
   },
   pickerOptionsEnd() {
     return {
       disabledDate: time => {
         if (this.checkFieldFormData && this.checkFieldFormData.fromDate) {
           const resDate = (new Date(time).getFullYear() + '-' + this.pMonth(new Date(time).getMonth() + 1)).replace(/-/g, '')
           return resDate < this.checkFieldFormData.fromDate
         }
       }
     }
   }
 },

pMonth(s) {
   return s < 10 ? '0' + s : s
 },