stopping mousewheel event from happening twice in OSX

Question

I noticed mousewheel event is happening multiple times in mac osx. Can be atributed to inertia feature.

Is there a way to fix this behaviour?

(self signed ssl no

Answer 1

You know, I think it's a better idea to use timeouts in this case. Why not write something like this:

// Let's say it's a global context or whatever...:
var fireEvent = true;
var newDelta, oldDelta, eventTimeout;
newDelta = oldDelta = eventTimeout = null;

// ... and the function below fires onmousewheel or anything similar:
function someFunc(){
    if(!fireEvent) return; // if fireEvent is not allowed => stop execution here ('return' keyword stops execution of the function), else, execute code below:
    newDelta = deltaY;
    if(oldDelta!=null&&oldDelta*newDelta>0){ // (1.1) if it's not the first event and directions are the same => prevent possible dublicates for further 50ms:
        fireEvent = false;
        clearTimeout(eventTimeout); // clear previous timeouts. Important!
        eventTimeout = setTimeout(function(){fireEvent = true},500);
    }
    oldDelta = newDelta;
    someEventCallback(); // (1.2) fire further functions...
    }

So, any mousewheel event fired within half a second after any previous mousewheel event call will be ignored, if it is made in the same direction as previous (see condition at 1.1). It will solve the problem and there's no way user would spot this. Delay amount may be changed to better meet your needs.

The solution is made on pure JS. You're welcome to ask any questions about integrating it in your environment, but then I'll need you to provide further code of your page.

P.S. I have not seen anything similar to eventCallback() call in your code (see 1.2 of my solution). there was only fireEvent flag. Were you doing something like:

if(fireEvent)
    someEventCallback();

later on or something?

P.P.S.note that fireEvent should be in global scope in order to work here with setTimeout. If it's not, it's also quite easy to make it work fine, but the code needs to be altered a bit. If it's your case, tell me and I'll fix it for you.

UPDATE

After a brief search I found out, that similar mechanism is used in Underscore's _debounce() function. See Underscore documentation here