无缝滚动改进版支持上下左右滚动（封装成函数）_javascript技巧

代码如下:
/**********
功能：实现水平或垂直无缝滚动
参数：direction方向，总共4个值：left,right,top,bottom
speed移动距离
iTime多少时间后开始移动，若不写则页面加载完开始移动
**********/
function scroll(direction,speed,iTime){
var oDiv = document.getElementById('scroll');
var oUl = oDiv.getElementsByTagName('ul')[0];
var aLi = oDiv.getElementsByTagName('li');
var aBtn = oDiv.getElementsByTagName('a');
var timer = null;
var iSpeed = 0;
var flag = true; //判断水平移动还是垂直移动

oUl.innerHTML += oUl.innerHTML;

switch(direction){
case 'left':
iSpeed = -speed;
oUl.style.width = aLi[0].offsetWidth * aLi.length + 'px';
flag = true;
break;
case 'right':
iSpeed = speed;
oUl.style.width = aLi[0].offsetWidth * aLi.length + 'px';
flag = true;
break;
case 'top':
iSpeed = -speed;
flag = false;
break;
case 'bottom':
iSpeed = speed;
flag = false;
break;
};

setTimeout(move,iTime);

//左按钮和上按钮
aBtn[0].onclick = function(){
clearInterval(timer);
iSpeed = -speed;
move();
};

//右按钮和下按钮
aBtn[1].onclick = function(){
clearInterval(timer);
iSpeed = speed;
move();
};

oUl.onmouseover = function(){
clearInterval(timer);
};

oUl.onmouseout = function(){
move();
};

function move(){
timer = setInterval(function(){
if(flag){
oUl.style.left = oUl.offsetLeft + iSpeed + 'px';
if(oUl.offsetLeft < -oUl.offsetWidth / 2){
oUl.style.left = '0';
}else if(oUl.offsetLeft > 0){
oUl.style.left = - oUl.offsetWidth / 2 + 'px';
}
}else{
oUl.style.top = oUl.offsetTop + iSpeed + 'px';
if(oUl.offsetTop <= - oUl.offsetHeight / 2){
oUl.style.top = '0';
}else if(oUl.offsetTop >= 0){
oUl.style.top = - oUl.offsetHeight / 2 + 'px';
};
};
},30);
};
};

需要注意的是：html 结构必须要像上面的结构一样。