textarea组件超出最大值

<view class="group">  
      <view class="item">  
        <view class="label">访问事由</view>  
        <view class="nums"  
          ><text>{{ query.reason.length }}/</text>50</view  
        >  
      </view>  
      <view class="item">  
        <view class="info">  
          <textarea  
            auto-height  
            maxlength="50"  
            v-model="query.reason"  
            placeholder="请输入"  
            placeholder-style="color: #cacaca"  
          ></textarea>  
        </view>  
      </view>  
    </view>

    auto-height    
    maxlength="50"    
    v-model="query.reason"    
    placeholder="请输入"    
    placeholder-style="color: #cacaca"    
    @input="bindTextAreaBlur"  
></textarea>```                                                                                                                                                                
 ```javascript  
 bindTextAreaBlur2: function (e) {  
    let maxValue = e.detail.value  
    if(maxValue.length>=50){  
    this.$nextTick(()=>{  
         this.query.reason=e.detail.value.substring(0,50)  
        })  
    }  
   }