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From: Arno Welzel <usenet@arnowelzel.de>
Newsgroups: comp.lang.javascript
Subject: Re: Stop the mouse listener
Date: Thu, 24 Sep 2020 10:14:04 +0200
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Xref: csiph.com comp.lang.javascript:38837

Jonas Thörnvall:

> Den onsdag 23 september 2020 kl. 13:49:32 UTC+2 skrev JJ:
>> On Wed, 23 Sep 2020 00:16:47 -0700 (PDT), Jonas Thörnvall wrote:
>>> I want to stop the mouse listener while player scroll thru moves
>>> previous "board locked for moves". But i do not manage to turn
>>> listener off. I can see the alert but the listener still run so
>>> board never lockdown?
>>> 
>>> function stop_listeners() { alert("test"); 
>>> c.removeEventListener('mouseup', start_listener); 
>>> c.removeEventListener('mousedown', start_listener); 
>>> c.removeEventListener('mousemove', start_listener); }
>>> 
>>> // Start listener function start_listener() { mousePos = [0, 0]; 
>>> mouseDown = [0, 0]; mouseUp = [0, 0]; 
>>> c.addEventListener("mouseup", function(evt) {
>> [snip]
>> 
>> You never did stop the listeners. `start_listener` is not even used
>> as an event handler.
> 
> I am not sure what you do say JJ, that if i call function
> start_listener it have not started the listeners, how come they work
> then. I just ask for howto remove them...?

You did NOT use "start_listener" for the event listener!

You said:

c.addEventListener('mousemove', function(evt) {
       mousePos = getPosition(ctm, evt);
       message = 'Mouse position: ' + mousePos.x + ',' + mousePos.y;
    }, false);

and NOT:

c.addEventListener('mousemove', start_listener);

If you want to add a listener which should be removable, you must do
that in this way:

function myListener(evt) {
...
}

c.addEventListener('mousemove', myListener);
...
c.removeEventListener('mousemove', myListener);


Also see:

<https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/removeEventListener#Matching_event_listeners_for_removal>



-- 
Arno Welzel
https://arnowelzel.de