检查一个输入框为空 [英] Check if a input box is empty

问题描述

我如何检查是否给定的输入控件是空的？我知道有 $质朴告诉在球场上的属性，如果某一领域最初是空的，但如果什么时候有人填写字段并再次猛拉的全部内容？

How can I check if a given input control is empty? I know there is $pristine property on the field which tells that if a given field is empty initially but what if when someone fill the field and yanks the whole content again?

我觉得上面的功能是必要的，因为它告诉，要求外地用户非常重要的。

I think above feature is necessary as its important for telling the user that field is required.

任何想法将AP preciated！

Any idea will be appreciated!

推荐答案

很简单：

<input ng-model="somefield">
<span ng-show="!somefield.length">Please enter something!</span>
<span ng-show="somefield.length">Good boy!</span>

您也可以使用 NG-隐藏=somefield.length而不是 NG-秀=！somefield.length如果你读自然更多。

You could also use ng-hide="somefield.length" instead of ng-show="!somefield.length" if that reads more naturally for you.

有一个更好的选择可能是真正地角的形式的能力优势：

A better alternative might be to really take advantage of the form abilities of Angular:

<form name="myform">
  <input name="myfield" ng-model="somefield" ng-minlength="5" required>
  <span ng-show="myform.myfield.$error.required">Please enter something!</span>
  <span ng-show="!myform.myfield.$error.required">Good boy!</span>
</form> 

这里更新Plnkr。

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