//이미지 슬라이더
window.onload = function() {
	//res = document.getElementById("result");
	imageSlider(57, 1); // Move Width, Move Item Count
}

	function imageSlider(w, cnt) {
		// Global Variable
		imageList = new Object();
		item_width = w*cnt;
		curr_position = 0;
		curr_idx = 0;
		tmp = 0;

		var slider = document.getElementById("imageSlider");
		var groups = slider.getElementsByTagName("div");

	for(var i=0; i < groups.length; i++) {
	
	if(groups[i].className == "imageList") imageList = groups[i].getElementsByTagName("ul")[0]; // Image List (UL Element)
}
		var lis = imageList.getElementsByTagName("li");
		imageList.style.width = (w * lis.length) + "px";

		// Controller
		var bts = slider.getElementsByTagName("img");
	for(var i=0; i<bts.length; i++) {
	
	if(bts[i].className == 'btn_prev') {

		bts[i].onclick = function() { sliderPrev(cnt); } // Click To Prev
}
else if(bts[i].className == 'btn_next')
{
bts[i].onclick = function() { sliderNext(cnt); } // Click To Next
}
}
}

function sliderNext(cnt) // Next Behavior
{
var slider = document.getElementById("imageSlider");
var groups = slider.getElementsByTagName("div");
var bts = groups[0].getElementsByTagName("img");
var nextNum=bts.length-3;
if(bts.length<=3) nextNum=0;

if(curr_idx < nextNum)
{
imageList.style.left = (curr_position - item_width) + "px";
curr_position -= item_width;
for(var i=0; i<cnt; i++) curr_idx++;
//res.innerHTML = "Index : " + curr_idx;
//res.className = "";
}
else
{
alert("마지막입니다.");
}
}


function sliderPrev(cnt) // Prev Behavior
{
if(curr_idx > 0)
{
imageList.style.left = (curr_position + item_width) + "px";
curr_position += item_width;
for(var i=0; i<cnt; i++) curr_idx--;

}
else
{
	alert("처음입니다.");
}
}