required 和 ng-required 有什么区别? [英] What is the difference between required and ng-required?

问题描述

required 和 ng-required(表单验证)有什么区别?

What is the difference between required and ng-required (form validation)?

推荐答案

AngularJS 表单元素寻找 required 属性来执行验证功能.ng-required 允许您根据布尔测试设置 required 属性(例如，只需要字段 B - 比如说，一个学生号- 如果字段 A 具有特定值 - 如果您选择了学生"作为选项)

AngularJS form elements look for the required attribute to perform validation functions. ng-required allows you to set the required attribute depending on a boolean test (for instance, only require field B - say, a student number - if the field A has a certain value - if you selected "student" as a choice)

举个例子， 和 本质上是一回事

As an example, <input required> and <input ng-required="true"> are essentially the same thing

如果您想知道为什么这是这种方式，(而不仅仅是使 或 )，这是由于 HTML 的限制 - required 属性没有关联的值 - 它的存在意味着(根据 HTML 标准)该元素是必需 - 所以 angular 需要一种设置/取消设置所需值的方法(required="false" 将是无效的 HTML)

If you are wondering why this is this way, (and not just make <input required="true"> or <input required="false">), it is due to the limitations of HTML - the required attribute has no associated value - its mere presence means (as per HTML standards) that the element is required - so angular needs a way to set/unset required value (required="false" would be invalid HTML)

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