jquery - How can I avoid autorepeated keydown events in JavaScript?

Question

If the user holds down the key, multiple keydown events are fired. For usability reasons I need to use keydown, not keyup, but I want to avoid this situation. My relevant code is the following:

$(document).keydown(function(e) { 
        var key = 0;


        if (e == null) { key = event.keyCode;}  
        else {  key = e.which;} 


        switch(key) {
            case config.keys.left:                
              goLeft();
              break;
            case config.keys.up:                        
              goUp();
              break;
            case config.keys.right:                     
              goRight();
              break;
            case config.keys.down:                
              goDown();
              break;
            case config.keys.action:              
              select();
              break;
        }     
      });

So when the user holds down the down key, for example, goDown() is fired multiple times. I would like it to fire just once even if the user holds the key down.

Answer 1

Use event.repeat to detect whether or not the event is repeating. You could then wait for "keyup" before allowing the handler to execute a second time.

var allowed = true;

$(document).keydown(function(event) { 
  if (event.repeat != undefined) {
    allowed = !event.repeat;
  }
  if (!allowed) return;
  allowed = false;
  //...
});

$(document).keyup(function(e) { 
  allowed = true;
});
$(document).focus(function(e) { 
  allowed = true;
});