<script type="text/javascript">

	var slider_content = document.getElementById('box');

	// contain images in an array
	 var image = ['a', 'b', 'c','e'];

	 var i = image.length;

	//function for next slide

	 function nextImage(){
		 if (i < image.length){
			 i= i+1;
		 }else{
			 i = 1;
		 }
			slider_content.innerHTML = "<img src="+image[i-1]+".jpg>";
	 }


   </script>