問題描述

我正在嘗試編寫一個 Angular2 屬性指令來修改某些元素的行為.更具體地說，我想將屬性應用于具有點擊處理程序的某些元素，并防止綁定函數在某些條件下執行.

I am trying to write a Angular2 attribute directive to modify the behaviour of certain elements. More specifically I want to apply an attribute to certain elements that have click handlers and prevent the bound function to be executed under certain conditions.

所以現在我有一個元素，例如:

So now I have an element e.g.:

<button (click)="onClick(param1, param2)"></button>

onClick 是在承載按鈕元素的組件上聲明的函數.

onClick is a function declared on the component that hosts the button element doing some work.

我想做的是這樣寫:

<button (click)="onClick(param1, param2)" online-only></button>

并有一個類似的指令:

@Directive({
  selector: '[online-only]',
})
export class OnlineOnlyDirective {
  @HostListener('click', ['$event']) 
  onClick(e) {
    if(someCondition){
      e.preventDefault();
      e.stopPropagation();
    }
  }
}

但是單擊處理程序首先執行，因此我的指令沒有機會停止執行.

But click handler is executed first, thus not giving my directive the opportunity to stop its execution.

我想到的第二種方法是用我自己的處理程序替換(單擊)，例如([onlineClick]="onClick")并在指令認為合適時執行傳遞的函數，但是這樣我不能將參數傳遞給 onClick 函數和看起來有點奇怪.

A second approach I thought about was replacing (click) with my own handler e.g.( [onlineClick]="onClick" ) and execute the passed function when the directive thinks fit, but this way I cannot pass params to onClick function and is a bit weirder to look at.

你對做這樣的事情有什么想法嗎?

Do you have any thoughts on doing something like that?

推薦答案

我不知道有什么方法可以強制 Angular 先執行某個事件處理程序.一種解決方法可能是使用自定義事件，例如:

I don't know of a way to force Angular to execute a certain event handler first. A workaround might be to use a custom event like:

<button (myClick)="onClick(param1, param2)" online-only></button>

@Directive({
  selector: '[myClick]',
})
export class OnlineOnlyDirective {
  @Output() myClick: EventEmitter = new EventEmitter();
  @HostListener('click', ['$event']) 
  onClick(e) {
    if(someCondition){
      e.preventDefault();
      e.stopPropagation();
    } else {
      this.myClick.next(e);
    }
  }
}

這篇關于Angular2指令修改點擊處理的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！