Landing Page

<script> 
    window.onload = function() { 
   
        // Index of current image 
        // which is on display 
        var imageIndex = 0; 
   
        // Object array of all the 
        // images of class test 
        var images =  
            document.getElementsByClassName('test'); 
   
        // This tells us if mouse if over 
        // image or not, We only change 
        // image if mouse if over it 
        var isMouseOverImage = false; 
   
        // Object of parent element  
        // containing all images 
        var scrollImages =  
            document.getElementById('scroll-image'); 
   
        // Stores the current scoll co-ordinates 
        // so that the window don't scroll down 
        // while scrolling the images 
        var x, y; 
   
        // This function sets the scroll to x, y 
        function noScroll() { 
            window.scrollTo(x, y); 
        } 
   
        // The following event id fired once when  
        // We hover mouse over the images 
        scrollImages.addEventListener( 
                "mouseenter", function() { 
   
            // We store the current page 
            // offset to x,y 
            x = window.pageXOffset; 
            y = window.pageYOffset; 
   
            // We add the following event to 
            // window object, so if we scroll 
            // down after mouse is over the  
            // image we can avoid scrolling 
            // the window 
            window.addEventListener("scroll", noScroll); 
              
            // We set isMouseOverImage to 
            // true, this means Mouse is 
            // now over the iamge 
            isMouseOverImage = true; 
        }); 
   
        // The following function is fired 
        // when mouse is no longer over 
        // the images 
        scrollImages.addEventListener( 
                "mouseleave", function() { 
   
            // We set isMouseOverImage to 
            // false, this means mouse is 
            // not over the iamge 
            isMouseOverImage = false; 
   
            // We remove the event we previously 
            // added because we are no longer 
            // over the image, the scroll will 
            // now scroll the window 
            window.removeEventListener( 
                        "scroll", noScroll); 
        }); 
   
        // The following function is called 
        // when we move mouse wheel over 
        // the images 
        scrollImages.addEventListener( 
                    "wheel", function(e) { 
                              
            // We check if we are over 
            // image or not 
            if (isMouseOverImage) { 
                var nextImageIndex; 
   
                // The following condition 
                // finds the next image 
                // index depending if we 
                // scroll up or scroll down 
                if (e.deltaY > 0) 
                    nextImageIndex = (imageIndex + 1) 
                                     % images.length; 
                else
                    nextImageIndex =  
                            (imageIndex - 1 
                            + images.length) 
                            % images.length; 
   
                // We set the z index of current 
                // image to 0 
                images[imageIndex].style.zIndex = "0"; 
                      
                // We set the z index of next 
                // image to 1, this makes  
                // The new image appear on top 
                // of old image 
                images[nextImageIndex].style.zIndex = "1"; 
                imageIndex = nextImageIndex; 
            } 
        }); 
    } 
</script>