angular1.x中 输入框中怎么验证输入了回车键？防止验证报错？

Question

<textarea ng-model="mailInfo.messageContent" rows="10" 
    class="form-control" placeholder="1 ~ 2000个字符" 
    style="border-radius:3px!important" required  
    ng-pattern="/^.{1,2000}$/" 
    ng-pattern-err-type="1 ~ 2000个字符"> 
</textarea>