var width = 740;
var animationSpeed = 1000;
var pause = 3000;
var currentSlide = 1;
var interval;
var timer;

function slide() {
    timer = function () {
        interval = setInterval(function () {
            if(currentSlide === $("#slides").children().length) width = 0;
            else width = 740;
            $("#slides").animate({'margin-left': '-=' + width}, animationSpeed, function () {
                if (++currentSlide > $("#slides").children().length) {
                    currentSlide = 1;
                    $("#slides").animate({'margin-left': 0}, animationSpeed);
                    clearInterval(interval);
                    timer();
                }
            });
        }, pause);
    }
}

function next() {
    console.log("Going forward:" + currentSlide,$("#slides").children().length - 1);
    if (currentSlide <= $("#slides").children().length - 1) {
        $("#slides").animate({'margin-left': '-=' + width}, animationSpeed, function () {
            currentSlide += 1;
        });
        clearInterval(interval);
        timer();
    }

}

function previous() {
    console.log("Going back:" + currentSlide,$("#slides").children().length - 1);
    if (currentSlide >= $("#slides").children().length - 1) {
        $("#slides").animate({'margin-left': '+=' + width}, animationSpeed, function () {
            currentSlide -= 1;
        });
        clearInterval(interval);
        timer();
    }
}