[ruslan_mart]

var delay = 2000,
    callback = function() {
        nextSlide(1);
        timeoutId = null;
    },
    timeoutId = setTimeout(callback, delay),
    time = Date.now();;

$("#blok").mouseenter(function() {
    clearTimeout(timeoutId);
}).mouseleave(function() {
    if(timeoutId) {
        var n = Date.now() - time;

        if(n > delay) {
            callback();
        }
        else {
            timeoutId = setTimeout(callback, delay - n);
        }
    }
});