仿twitter微博首页的自动无缝滚动

一个仿twitter/新浪微博首页的自动无缝滚动效果，相信可以用到这个效果的地方很多。这种效果可以给用户带来相当不错的信任感，说明网站的实时性、活跃度都不错。加上懒加载的效果，相当人性化。

效果演示

欢迎访问简明现代魔法！






欢迎访问简明现代魔法！X2






欢迎访问简明现代魔法！X3






欢迎访问简明现代魔法！X4








调用方式如下：

<script type="text/javascript">
new slider({
    id:'slider', //必选：滚动ul的id
    auto:4 //可选，滚动间隙，默认3秒
})
</script>

JavaScript代码：

<script type="text/javascript">
<!--
function H$(i) {return document.getElementById(i)}
function H$$(c, p) {return p.getElementsByTagName(c)}
var slider = function () {
	function init (o) {
		this.id = o.id;
		this.at = o.auto ? o.auto : 3;
		this.o = 0;
		this.pos();
	}
	init.prototype = {
		pos : function () {
			clearInterval(this.__b);
			this.o = 0;
			var el = H$(this.id), li = H$$('li', el), l = li.length;
			var _t = li[l-1].offsetHeight;
			var cl = li[l-1].cloneNode(true);
			cl.style.opacity = 0; cl.style.filter = 'alpha(opacity=0)';
			el.insertBefore(cl, el.firstChild);
			el.style.top = -_t + 'px';
			this.anim();
		},
		anim : function () {
			var _this = this;
			this.__a = setInterval(function(){_this.animH()}, 20);
		},
		animH : function () {
			var _t = parseInt(H$(this.id).style.top), _this = this;
			if (_t >= -1) {
				clearInterval(this.__a);
				H$(this.id).style.top = 0;
				var list = H$$('li',H$(this.id));
				H$(this.id).removeChild(list[list.length-1]);
				this.__c = setInterval(function(){_this.animO()}, 20);
				//this.auto();
			}else {
				var __t = Math.abs(_t) - Math.ceil(Math.abs(_t)*.07);
				H$(this.id).style.top = -__t + 'px';
			}
		},
		animO : function () {
			this.o += 2;
			if (this.o == 100) {
				clearInterval(this.__c);
				H$$('li',H$(this.id))[0].style.opacity = 1;
				H$$('li',H$(this.id))[0].style.filter = 'alpha(opacity=100)';
				this.auto();
			}else {
				H$$('li',H$(this.id))[0].style.opacity = this.o/100;
				H$$('li',H$(this.id))[0].style.filter = 'alpha(opacity='+this.o+')';
			}
		},
		auto : function () {
			var _this = this;
			this.__b = setInterval(function(){_this.pos()}, this.at*1000);
		}
	}
	return init;
}();
// -->
</script>