Shimpanze

!true = false
!false = true

text = false
if(!text){
//Условие выполняется
}

!42 = false
!0 = true

!null = true
!"some text" = false
!"42" = false
!"0" = false

function auto_play() {
	var act = $('.controlNav > li.act');
	act.next().trigger('click');
}

var autoPlay = setInterval( auto_play, 4000 );

slider.hover(function(){
	clearInterval(autoPlay);
}, function(){
	autoPlay = setInterval( auto_play, 4000 );
});

var timer;
function a() {
  !timer || clearTimeout(timer);
  timer = setTimeout(function() { 
    console.log('Выполнение...');
  }, 2000);
}

document.getElementById('content').addEventListener('keyup', a);