Traverse Array With Onclick?

I'm working on an image gallery at the moment and I'm having some trouble with the array the the images are stored in. The issue I'm having is that I can't figure out how to increase and decrease the current element in an array with the onclick event. Here's what I'm thinking so far:

var imageList = ['a','b','c','d','e'];
var position=0;
currentImage=imageList[position];

if a link with the id of "leftClick" is clicked, then position should decrease by 1 but if a link with the id of "rightClick" is clicked, then position should increase by 1 Both of these conditions should be bound to imageList.length i.e. if (position<0){position=0}; and if (position>imageList.length){position=imageList.length}; So how can I make "position" increase or decrease by clicking a link using the onclick event?