限制验证码输入框输入长度

src/components/PhoneCodeLoginPopup.vue

@@ -3,7 +3,7 @@
     <h5>手机号登录</h5>
     <van-form :show-error="false" @submit="handleSuccess">
       <van-field v-model="form.mobile" name="mobile" label="手机号" placeholder="请输入您的手机号" :rules="[{ required: true, message: '请输入您的手机号' }, { pattern: /^1(3[0-9]|4[01456879]|5[0-35-9]|6[2567]|7[0-8]|8[0-9]|9[0-35-9])\d{8}$/, message: '手机号格式有误' }]" clearable/>
-      <van-field v-model="form.code" name="code" label="验证码" placeholder="请输入手机验证码" :rules="[{ required: true, message: '请输入手机验证码' }]" clearable>
+      <van-field v-model="form.code" name="code" label="验证码" placeholder="请输入手机验证码" :rules="[{ required: true, message: '请输入手机验证码' }]"  maxlength="4" clearable>
         <template #button>
           <van-button class="code-btn" native-type="button" size="small" type="primary" color="#F8F8F8" :disabled="btnDisabled" id="checkedCode" @click="sendCode">获取验证码</van-button>
         </template>