el-select可搜索功能，实现对输入的搜索内容进行控制，比如控制长度，清除前后空格

<el-select
  multiple
  collapse-tags
  @change="change"
  @input.native="filterData"
  ref="searchSelect"
  v-model="searchData.selectTxt"
  filterable
  placeholder="请选择"
>
  <el-option
    v-for="subitem in options"
    :key="subitem.value"
    :label="subitem.label"
    :value="subitem.value"
  ></el-option>
</el-select>


```
filterData() {
    const str = this.$refs.searchSelect.$data.selectedLabel;
    console.log(this.$refs.searchSelect.$data.selectedLabel);
    // 清空前后空格
    this.$refs.searchSelect.$data.selectedLabel = str.trim();
    // 控制输入的长度
    if(str.length>20) this.$refs.searchSelect.$data.selectedLabel = str.substr(0,21)
    
}
```