问题描述
可以对NgForm的valueChanges可观察属性订阅回调，以便对表单控件的值的变化做出反应.
It is possible to subscribe a callback to an NgForm's valueChanges observable property in order to react to changes in the values of the controls of the form.
我需要以相同的方式对用户触摸表单控件之一的事件做出反应.
I need, in the same fashion, to react to the event of the user touching one of the form controls.
此类似乎定义了valueChanges Observable，而touched属性定义为布尔值.
This class seem to define the valueChanges Observable and the touched property is defined as a boolean.
是否可以对触摸控件"事件做出反应?
推荐答案
ng2没有提供直接的方式对触摸事件做出反应.它使用( input )事件触发 valueChanges 事件和( blur )事件来设置 touched/untouched 属性 AbstractControl .因此，您需要在模板中手动订阅所需的事件，并在组件类中对其进行处理.
There is not direct way provided by ng2 to react on touched event. It uses (input) event to fire the valueChanges event and (blur) event to set touched/untouched property of AbstractControl.So you need to manually subscribe on desired event in the template and handle it in your component class.
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