function change() //动画开启
{
flag = setInterval(callback,2000);
}

function off() //onmouSEOver事件发生，动画暂停
{
clearInterval(flag);
}

function on() //onmouSEOut事件发生，动画继续
{
flag = setInterval(callback,2000);
}

function leftMove() //实现左滑动
{
document.getElementById("photo").src = photos[count];
count++;
if (count == photos.length)
count = 0;
}

function rightMove() //实现右滑动
{
count--;
document.getElementById("photo").src = photos[count];
if (count <= 0)
count = photos.length - 1;
}