name1

/**delta function is to set how the image slide—keep still for a while and move to next picture.
*step function will be called many times until clearInterval() been called
* currentImage * imageWidth is the currentImage position of ul
* delta start from 0 to 1, delta * imageWidth is the pixels that changes
**/
 function slider(ul){ 
    animate({
        delay:17,
        duration: 3000,
        delta:function(p){return Math.max(0, -1 + 2 * p)},
        step:function(delta){
            ul.style.left = ‘-’ + parseInt(currentImage * imageWidth + delta * imageWidth) + ‘px’;
    },
        callback:function(){
            currentImage++;
        // if it doesn’t slied to the last image, keep sliding
            if(currentImage < imageNumber-1){
                slider(ul);
        }
       // if current image it’s the last one, it slides back to the first one
            else{
                var leftPosition = (imageNumber - 1) * imageWidth;
               // after 2 seconds, call the goBack function to slide to the first image 
                setTimeout(function(){goBack(leftPosition)},2000); 
                setTimeout(function(){slider(ul)}, 4000);
            }
        }
    });
}