检查输入框是否为空 [英] Check if a input box is empty

问题描述

如何检查给定的输入控件是否为空?我知道该字段上有 $pristine 属性，该属性表明给定字段最初是否为空，但是如果有人填写该字段并再次拉取整个内容怎么办?

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?

我认为上述功能是必要的，因为它告诉用户该字段是必需的.

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

任何想法将不胜感激！

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-hide="somefield.length" 而不是 ng-show="!somefield.length" 如果这对您来说更自然.

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

更好的选择可能是真正利用 Angular 的表单功能:

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> 

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