nativeElement.click()和事件处理程序的点击之间有什么区别? [英] What is the difference between nativeElement.click() and event handler's click?
问题描述
我一直在尝试对角度2应用程序进行测试,该应用程序单击调用函数的提交按钮.我通常使用两种方法执行相同的操作.
I have been trying to perform a test for angular 2 application that clicks a submit button which calls a function. I usually use two methods to perform the same.
element.nativeElement.click()
和
element.triggerEventHandler('click',null);
我以为这两种方法都是相同的,直到遇到触发事件处理程序方法不起作用的情况.
I thought both these methods were same, until I came across this situation where triggering event handler method does not work.
element = fixture.debugElement.query(By.css('.dropList li'));
element.triggerEventHandler('click',null); //Click event works here
fixture.detectChanges();
let button = fixture.debugElement.query(By.css('button'));
//button.triggerEventHandler('click',null); //Does not call function
button.nativeElement.click(); //Calls function
fixture.detectChanges();
模板供您参考:
<form (ngSubmit)="printSelection()">
<div class="dropList">
<ul>
<li *ngFor="let element of data.elements" (click)="selectElement(element)"> </li>
</ul>
</div>
<button type="submit">Submit</button>
</form>
那么,这两种方法之间是否有任何区别,或者您认为我的代码在某些地方可能出错了?
So, are there any difference between these two approaches or do you think I may have gone wrong somewhere in my code?
推荐答案
element.nativeElement.click()
是原生方法,用于模拟鼠标点击在一个元素上.它正在冒泡,其行为与单击元素时相同.
is native method to simulate a mouse click on an element. It's bubbling and it behaves in the same way as if we click on the element.
debugElement.triggerEventHandler(eventName,eventObj)
是一个内置的角度方法,它仅在当前调试元素上为给定的eventName调用所有侦听器:
is angular built-in method that just calls all listeners for given eventName on current debug element:
triggerEventHandler(eventName: string, eventObj: any) {
this.listeners.forEach((listener) => {
if (listener.name == eventName) {
listener.callback(eventObj);
}
});
}
当DebugRenderer2
运行listen
方法时,添加
侦听器:
Listeners are added when DebugRenderer2
runs listen
method:
listen(
target: 'document'|'windows'|'body'|any, eventName: string,
callback: (event: any) => boolean): () => void {
if (typeof target !== 'string') {
const debugEl = getDebugNode(target);
if (debugEl) {
debugEl.listeners.push(new EventListener(eventName, callback));
}
}
return this.delegate.listen(target, eventName, callback);
}
当我们将事件绑定应用于像这样的元素时,就会发生
It happens when we apply event binding to element like
-
(click)="handler()"
-
@HostListener('click')
-
host: '{ '(mouseenter): 'handler()' }
-
renderer.listen
(click)="handler()"
@HostListener('click')
host: '{ '(mouseenter): 'handler()' }
renderer.listen
假设我们有以下模板:
<div (click)="test()">
<div class="innerDiv">
{{title}}
</div>
</div>
我们的测试如下:
de = fixture.debugElement.query(By.css('.innerDiv'));
de.nativeElement.click(); // event will be bubbled and test handler will be called
de.triggerEventHandler('click', null); // there is not handlers for click event
// that angular added to this element
// so test method won't be called
然后让我们看一下您的模板.没有用于button
的处理程序,因此triggerEventHandler
不会有任何作用.另一方面,button.nativeElement.click();
会触发提交,因为按钮的类型为Submit,而单击事件中按钮的标准行为.
Then let's look at your template. There is no handlers for button
so triggerEventHandler
won't have any effect. On the other hand button.nativeElement.click();
will fire submit because button has type submit and its standart behaviour of button on click event.
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