js 实现单行文本滚动效果

js 代码如下：

/***************滚动场次开始*****************/

function ScrollText(content, btnPrevious, btnNext, autoStart) {
    this.Delay = 10;
    this.LineHeight = 20;
    this.Amount = 1; 
    this.Direction = "up";
    this.Timeout = 1500;
    this.ScrollContent = this.$(content);
    this.ScrollContent.innerHTML += this.ScrollContent.innerHTML;
    //this.ScrollContent.scrollTop = 0;
    if (btnNext) {
        this.NextButton = this.$(btnNext);
        this.NextButton.onclick = this.GetFunction(this, "Next");
        this.NextButton.onmouseover = this.GetFunction(this, "Stop");
        this.NextButton.onmouseout = this.GetFunction(this, "Start");
    }
    if (btnPrevious) {
        this.PreviousButton = this.$(btnPrevious);
        this.PreviousButton.onclick = this.GetFunction(this, "Previous");
        this.PreviousButton.onmouseover = this.GetFunction(this, "Stop");
        this.PreviousButton.onmouseout = this.GetFunction(this, "Start");
    }
    this.ScrollContent.onmouseover = this.GetFunction(this, "Stop");
    this.ScrollContent.onmouseout = this.GetFunction(this, "Start");
    if (autoStart) {
        this.Start();
    }
}

ScrollText.prototype.$ = function (element) {
    return document.getElementById(element);
}

ScrollText.prototype.Previous = function () {
    clearTimeout(this.AutoScrollTimer);
    clearTimeout(this.ScrollTimer);
    this.Scroll("up");
}

ScrollText.prototype.Next = function () {
    clearTimeout(this.AutoScrollTimer);
    clearTimeout(this.ScrollTimer);
    this.Scroll("down");
}

ScrollText.prototype.Start = function () {
    clearTimeout(this.AutoScrollTimer);
    this.AutoScrollTimer = setTimeout(this.GetFunction(this, "AutoScroll"), this.Timeout);
}

ScrollText.prototype.Stop = function () {
    clearTimeout(this.ScrollTimer);
    clearTimeout(this.AutoScrollTimer);
}

ScrollText.prototype.AutoScroll = function () {
    if (this.Direction == "up") {
        if (parseInt(this.ScrollContent.scrollTop) >= parseInt(this.ScrollContent.scrollHeight) / 2) {
            this.ScrollContent.scrollTop = 0;
        }
        this.ScrollContent.scrollTop += this.Amount;
    } else {
        if (parseInt(this.ScrollContent.scrollTop) <= 0) {
            this.ScrollContent.scrollTop = parseInt(this.ScrollContent.scrollHeight) / 2;
        }
        this.ScrollContent.scrollTop -= this.Amount;
    }
    if (parseInt(this.ScrollContent.scrollTop) % this.LineHeight != 0) {
        this.ScrollTimer = setTimeout(this.GetFunction(this, "AutoScroll"), this.Delay);
    } else {
        this.AutoScrollTimer = setTimeout(this.GetFunction(this, "AutoScroll"), this.Timeout);
    }
}

ScrollText.prototype.Scroll = function (direction) {
    if (direction == "up") {
        if (this.ScrollContent.scrollTop == 0) {
            this.ScrollContent.scrollTop = parseInt(this.ScrollContent.scrollHeight) / 2;
        }
        this.ScrollContent.scrollTop -= this.Amount;
    } else {
        this.ScrollContent.scrollTop += this.Amount;
    }
    if (parseInt(this.ScrollContent.scrollTop) >= parseInt(this.ScrollContent.scrollHeight) / 2) {
        this.ScrollContent.scrollTop = 0;
    }
    if (parseInt(this.ScrollContent.scrollTop) % this.LineHeight != 0) {
        this.ScrollTimer = setTimeout(this.GetFunction(this, "Scroll", direction), this.Delay);
    }
}

ScrollText.prototype.GetFunction = function (variable, method, param) {
    return function () {
        variable[method](param);
    }
}

if (document.getElementById("ul_round")) {
    var scrollup = new ScrollText("ul_round");
    scrollup.LineHeight = 40;        //单排文字滚动的高度
    scrollup.Amount = 1;            //注意:子模块(LineHeight)一定要能整除Amount.
    scrollup.Delay = 30;           //延时
    scrollup.Start();             //文字自动滚动
    scrollup.Direction = "up";   //默认设置为文字向上滚动
}
/***************滚动场次结束*****************/

html代码：

<ul id="ul_round">
                    <li>今天上午场<b class="c_c00">10:00-11:00</b>,
                            已经结束
                    </li>
                    <li>今天下午场<b class="c_c00">14:30-15:30</b>,
                            已经结束
                    </li>
                    <li>今天临时场次<b class="c_c00">16:00-16:15</b>,
                            已经结束
                    </li>
        
                    <li>今天上午场<b class="c_c00">10:00-11:00</b>,
                            已经结束
                    </li>
                    <li>今天下午场<b class="c_c00">14:30-15:30</b>,
                            已经结束
                    </li>
                    <li>今天临时场次<b class="c_c00">16:00-16:15</b>,
                            已经结束
                    </li>
        </ul>