Slider fix

slider.js

var sliderIndex = 0;
var refreshIntervalId;
var $images = $(".slide-group").children();

$(function(){
	var $bar = $('.slide-buttons');
	addButton("Previous", prev, $bar);
	addButton("Next", next, $bar);
})

function next(){
	sliderIndex = (sliderIndex<$images.length-1)?sliderIndex+1:0;
	slide();
}

function prev(){
	sliderIndex = (sliderIndex<0)?sliderIndex-1:$images.length-1;
	slide();
}
function slide(){
  $images.fadeOut();
  $($images[sliderIndex]).slideDown();
}

function validate() {
  if (document.getElementById('remember').checked) {
    refreshIntervalId = window.setInterval(next, 1000);
  } else {
    window.clearInterval(refreshIntervalId)
    refreshIntervalId = null;
  }
}

function addButton(name, click, $element){
	var $button = $("<button>");
	$button.text(name);
	$button.on('click', click);
	$element.append($button);
}