验证textarea输入框字数限制index.wxmlindex.js

index.wxml

<view class='feedback-cont'> 
   <textarea auto-focus="true" value="{{replyName}}" maxlength="200" bindinput="textareaCtrl"   placeholder-style="color:#999;" placeholder="留下评论，共同学习，一起进步" />
   <view class='fontNum'>{{content.length}}/200</view>
</view>

index.js

Page({
    data: {
        //初始化评论内容，如果是回复则通过传参为空
        content: "",
    },
    textareaCtrl: function (e) {
        if (e.detail.value) {
            this.setData({
            content: e.detail.value
        })
        } else {
            this.setData({
            content: ""
        })
      }
   }
})