hi i have a slideshow with forward and previous buttons.
I have this code inside a function , i post it as i think it is the relevant part.
Code:
function next(){
		if(that.current>3){
			that.current=0;
		}
		images[0].style.zIndex=1;
		images[3].style.zIndex=1;
		images[2].style.zIndex=1;
		images[1].style.zIndex=1;
		switch(that.current){
			case 0:
				if(that.repeat==0){
				images[0].style.visibility="visible";
				images[0].style.zIndex=6;
				showInfo(info[0],0);
				}else{
				images[0].style.zIndex=5;
				images[3].style.zIndex=6;
				fadeOut(images[3],0,images[0]);
				showInfo(info[0],0);
				}
				break;
			case 1:
				images[1].style.zIndex=5;
				images[0].style.zIndex=6;
				fadeOut(images[0],0,images[1]);
				showInfo(info[1],0);
				break;
			case 2:
				images[2].style.zIndex=5;
				images[1].style.zIndex=6;
				fadeOut(images[1],0,images[2]);
				showInfo(info[2],0);
				break;
			case 3:
				images[3].style.zIndex=5;
				images[2].style.zIndex=6;
				fadeOut(images[2],0,images[3]);
				showInfo(info[3],0);
				break;
	
		}
		that.repeat=1; 
	}
	function previous(){
		if(that.current<0){
			that.current=3;
		}
		images[0].style.zIndex=1;
		images[3].style.zIndex=1;
		images[2].style.zIndex=1;
		images[1].style.zIndex=1;
		switch(that.current){
			case 0:
				images[0].style.zIndex=6;
				images[3].style.zIndex=5;
				fadeOut(images[0],0,images[3]);
				showInfo(info[3],0);
				break;
			case 1:
				images[1].style.zIndex=6;
				images[0].style.zIndex=5;
				fadeOut(images[1],0,images[0]);
				showInfo(info[0],0);
				break;
			case 2:
				images[2].style.zIndex=6;
				images[1].style.zIndex=5;
				fadeOut(images[2],0,images[1]);
				showInfo(info[1],0);
				break;
			case 3:
				images[3].style.zIndex=6;
				images[2].style.zIndex=5;
				fadeOut(images[3],0,images[2]);
				showInfo(info[2],0);
				break;
	
		}
		that.repeat=1;
	}
	next();
	that.loop=setInterval(function(){that.current++;next();},5000);
	var linkNext=document.getElementById("next");
	linkNext.onclick=function(){clearInterval(that.loop);that.current++;next();}
	var linkPrev=document.getElementById("prev");
	linkPrev.onclick=function(){that.previous=1;clearInterval(that.loop);that.current--;previous();}
You can see the working script here http://web-in-a-box.co.cc/#
The problems is that when first clicked previous decrements
Code:
that.current
by 2, not by 1 as internded , for the first click. Next clicks are ok in the same function, but when you click next ,after you've clicked previous , next also increments by 2 .