删除按钮：先删除为空的输入框，再从下往上删除输入框

在点击删除按钮是他总是将第一个输入框/输入框内有数据的给删除掉；所以将代码改写为‘先删除为空的输入框，再从下往上删除输入框’

<el-col :span="12">
          <el-form-item v-for="(item,index) of add" :key="index" label="Number">
            <el-input style="width: 100%" show-word-limit maxlength="8" v-model.trim="item.adds"
                      @change="addChange(index)"></el-input>
          </el-form-item>
          <div style="margin-top: -20px">
            <el-button icon="el-icon-circle-close" @click="delNumber"></el-button>
            <el-button type="primary" plain @click="naxtAdd">+</el-button>
          </div>
        </el-col>

data(){
	return{
		add:[{
			adds:''
		}],
		base:{
			Number:''
		}
	}
}


delNumber(item, index) {
      if ( this.add.length <= 1 ) return false
      let addNull = 0;
      for ( item in this.add ) if ( !this.add[item].adds ) tapNull++
      if ( addNull > 0 ) {
        for ( item in this.add ) {
          if ( !this.add[item].adds ) {
            this.add.splice(item, 1)
          }
        }
      } else {
        this.add.splice(this.add.length - 1, 1)// 删除了数组中对应的数据也就将这个位置的输入框删除
      }
    },