Re: bind and addEventListener/removeEventListener

Path	csiph.com!.POSTED.208-71-239-109.cust.centrio.cz!not-for-mail
From	Cezary Tomczyk <cezary.tomczyk@gmail.com>
Newsgroups	comp.lang.javascript
Subject	Re: bind and addEventListener/removeEventListener
Date	Tue, 13 Aug 2019 20:43:44 +0200
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On 13/08/2019 20:29, Julio Di Egidio wrote:
> On Tuesday, 13 August 2019 17:43:17 UTC+2, Julio Di Egidio  wrote:
>> On Tuesday, 13 August 2019 17:28:29 UTC+2, Cezary Tomczyk  wrote:
>>> Bind
>>> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind
>>> creates a new function.
>>>
>>> Let's say we have #1:
>>>
>>> document.body.addEventListener('click', myExampleClass.method.bind(this));
>>>
>>> and then:
>>>
>>> document.body.removeEventListener('click', myExampleClass.method);
>>>
>>> based on my research it should not be correct as the function created by
>>> bind is different than the original passed by reference in
>>> document.body.removeEventListener.
>>>
>>> If it is not correct then the approach like:
>>>
>>> var myRef = myExampleClass.method.bind(this);
>>
>> myExampleObject please...
>>
>>> document.body.addEventListener('click', myRef);
>>> document.body.removeEventListener('click', myRef);
>>>
>>> should be more appropriate, I guess.
>>>
>>> Need some thoughts on that.
>>
>> Sounds correct to me.
> 
> But I think you could in fact do something like this:
> 
>    document.body.addEventListener('click', myobj.method.bind(this));
> 
>    document.body.removeEventListener('click', myobj.method.bind(this));
> 
> as long as the two happen within the same closure...
> 
> My point being, the two handlers do not have to match by some kind of
> low-level reference equality, it's about being the same closure (functions
> are closures in JS) and the comparison is essentially lexical (JS is a
> functional language).

That's the thing I am not sure - reference equality.

> (Anyone please correct me if I am wrong, cannot find the relevant piece of
> documentation right now: but I do remember using e.g. inline functions and
> other complications no prob...)

Okay, let's see if anyone else have opinions on that.

-- 
Cezary Tomczyk
http://www.ctomczyk.pl/

Thread

bind and addEventListener/removeEventListener Cezary Tomczyk <cezary.tomczyk@gmail.com> - 2019-08-13 17:28 +0200
  Re: bind and addEventListener/removeEventListener Julio Di Egidio <julio@diegidio.name> - 2019-08-13 08:43 -0700
    Re: bind and addEventListener/removeEventListener Julio Di Egidio <julio@diegidio.name> - 2019-08-13 11:29 -0700
      Re: bind and addEventListener/removeEventListener Cezary Tomczyk <cezary.tomczyk@gmail.com> - 2019-08-13 20:43 +0200
        Re: bind and addEventListener/removeEventListener Julio Di Egidio <julio@diegidio.name> - 2019-08-13 11:48 -0700
  Re: bind and addEventListener/removeEventListener Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2019-08-13 20:58 +0200
    Re: bind and addEventListener/removeEventListener Julio Di Egidio <julio@diegidio.name> - 2019-08-13 12:36 -0700

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