当回调绑定到另一个对象时，removeEventListener不起作用 [英] removeEventListener not working when callback is bound to another object

问题描述

我最近注意到，当回调传递给绑定到另一个对象的 addEventListener 函数时，调用 removeEventListener

I recently noticed that when a callback is passed to the addEventListener function that is bound to another object, calling removeEventListener later won't work.

示例：

/* 'this' is referencing e.g. a class */
element.addEventListener('click', this.clickHandler.bind(this))

/* the event listener won't be removed */
element.removeEventListener('click', this.clickHandler)

我找到了使用默认功能<$的解决方法当您将对象传递给 addEventListener 时被调用的c $ c> handleEvent 。

I found a workaround using the default function handleEvent that is being called when you pass an object to addEventListener.

/* 'this' is referencing e.g. a class */
element.addEventListener('click', this)

/* the event listener won't be removed */
element.removeEventListener('click', this)

this.handleEvent = function (e) {
  switch(e.type) {
    'click': { 
      this.clickHandler(e);
    }
  }
}

我写过此处。

但是，我是好奇为什么会这样？为什么 removeEventListener 找不到找到要删除的eventHandler？

But, I am curious about why is this happening? Why is that removeEventListener doesn't finds the eventHandler to remove it?

推荐答案

好的，我缺少的是 bind 总是返回一个新函数。这意味着我正在将一个不同的函数传递给 removeEventListener ，因此找不到将其删除的函数。

Ok, something that I was missing is that bind always returns a new function. This means that I was passing a different function to removeEventListener thus it couldn't find it to remove it.

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