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Javascript/JQuery How to prevent function from repeatedly executed when holding down key?

开发者 https://www.devze.com 2023-02-16 01:53 出处:网络
Let suppose we have the following JQuery Code: $(document).bind(\'keyup\', function(e) { arrows=((e.which)||(e.keyCode));

Let suppose we have the following JQuery Code:

$(document).bind('keyup', function(e) {    
    arrows=((e.which)||(e.keyCode));    
    switch (arrows){    
       case 37:
          executeMyfunction();     
          break;    
    }    
});

If a user holds down the left arrow key (37) the executeMyfunction() is repeatedly called.

How can I prevent this from happenin开发者_如何学运维g?

I thought keyup would trigger only if key is released but its not working (that's why I use keyup; keydown does not work either).


I believe you have to unbind the event. I think it should not be keyup, but keypress or keydown.

Probably something like this.

$(document).bind('keydown', function(e) {    
    arrows=((e.which)||(e.keyCode));    
    switch (arrows){    
       case 37:    
          executeMyfunction();    
          $(document).unbind('keydown');    
          break;    
    }
});

You will have to rebind the function on keyup if you want to use the event again:

$(document).bind('keyup', function(e) {        
    switch (arrows){    
      case 37:
         $(document).bind('keydown');
         break;
    }    
})

Look at: http://api.jquery.com/unbind/


Well, you can always debounce the call to your function. That is, if you want your function to be called after the event has not been fired for a short period of time.

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