为el-date-picker赋值

应用场景：
当一个日期改变的时候，另一个日期自动加13周显示

代码实现：

<template>
  <div>
            <el-date-picker
          v-model="form.forecastDate"
          @change="forecastDateChange"
          :picker-options="pickerOptions"
          type="date"
          placeholder="选择日期"
          style="width: 300px">
        </el-date-picker>
        <el-date-picker
          disabled
          v-model="form.applyTime"
          type="date"
          style="width: 300px">
        </el-date-picker>
  </div>
</template>
<script>
export default{
data(){
  return{
    form: {
      forecastDate: '',
      applyTime: '',
    },
  }
},
methods:{
    forecastDateChange(val){
      let newDate = new Date().setDate(val.getDate() + 12*7 + 6)
      this.form.applyTime = new Date(newDate)//交付时间在需求时间13周后
      this.form.returnDate = ''
    },
},
}
</script>