用 Javascript 实现锚点(Anchor)间平滑跳转

锚点(Anchor)相信很多人都不陌生,它方便访问者在页面的不同位置快速跳转,直接找到自己感兴趣的内容,如果说 RSS 是整个网站的摘要,那锚点就是一个页面的摘要,通常一个页面内容很多的时候,都会用锚点来定位。

但是锚点也有个问题,通常点击锚点后,页面会立即跳到目标位置,而本文介绍的方法,实现了锚点(Anchor)间平滑跳转,效果非常不错。

用 Javascript 实现锚点(Anchor)间平滑跳转 – 示例

 
<script type="text/javascript">
 
// 说明 :用 Javascript 实现锚点(Anchor)间平滑跳转
// 来源 :ThickBox 2.1
// 整理 :Yanfu Xie [xieyanfu@yahoo.com.cn]
// 网址 :http://www.codebit.cn
// 日期 :07.01.17
 
// 转换为数字
function intval(v)
{
	v = parseInt(v);
	return isNaN(v) ? 0 : v;
}
 
// 获取元素信息
function getPos(e)
{
	var l = 0;
	var t  = 0;
	var w = intval(e.style.width);
	var h = intval(e.style.height);
	var wb = e.offsetWidth;
	var hb = e.offsetHeight;
	while (e.offsetParent){
		l += e.offsetLeft + (e.currentStyle?intval(e.currentStyle.borderLeftWidth):0);
		t += e.offsetTop  + (e.currentStyle?intval(e.currentStyle.borderTopWidth):0);
		e = e.offsetParent;
	}
	l += e.offsetLeft + (e.currentStyle?intval(e.currentStyle.borderLeftWidth):0);
	t  += e.offsetTop  + (e.currentStyle?intval(e.currentStyle.borderTopWidth):0);
	return {x:l, y:t, w:w, h:h, wb:wb, hb:hb};
}
 
// 获取滚动条信息
function getScroll() 
{
	var t, l, w, h;
	
	if (document.documentElement && document.documentElement.scrollTop) {
		t = document.documentElement.scrollTop;
		l = document.documentElement.scrollLeft;
		w = document.documentElement.scrollWidth;
		h = document.documentElement.scrollHeight;
	} else if (document.body) {
		t = document.body.scrollTop;
		l = document.body.scrollLeft;
		w = document.body.scrollWidth;
		h = document.body.scrollHeight;
	}
	return { t: t, l: l, w: w, h: h };
}
 
// 锚点(Anchor)间平滑跳转
function scroller(el, duration)
{
	if(typeof el != 'object') { el = document.getElementById(el); }
 
	if(!el) return;
 
	var z = this;
	z.el = el;
	z.p = getPos(el);
	z.s = getScroll();
	z.clear = function(){window.clearInterval(z.timer);z.timer=null};
	z.t=(new Date).getTime();
 
	z.step = function(){
		var t = (new Date).getTime();
		var p = (t - z.t) / duration;
		if (t >= duration + z.t) {
			z.clear();
			window.setTimeout(function(){z.scroll(z.p.y, z.p.x)},13);
		} else {
			st = ((-Math.cos(p*Math.PI)/2) + 0.5) * (z.p.y-z.s.t) + z.s.t;
			sl = ((-Math.cos(p*Math.PI)/2) + 0.5) * (z.p.x-z.s.l) + z.s.l;
			z.scroll(st, sl);
		}
	};
	z.scroll = function (t, l){window.scrollTo(l, t)};
	z.timer = window.setInterval(function(){z.step();},13);
}
 
</script>

调用方式:

 
scroller(el, duration)
 
el : 目标锚点 ID
duration : 持续时间,以毫秒为单位,越小越快
 
<style type="text/css">
div.test {
	width:400px;
	margin:5px auto;
	border:1px solid #ccc;
}
div.test strong {
	font-size:16px;
	background:#fff;
	border-bottom:1px solid #aaa;
	margin:0;
	display:block;
	padding:5px 0;
	text-decoration:underline;
	color:#059B9A;
	cursor:pointer;
}
div.test p {
	height:400px;
	background:#f1f1f1;
	margin:0;
}
 
</style>
 
<div class="test">
	<a name="header_1" id="header_1"></a>
	<strong onclick="javascript:scroller('header_4', 800);">header_1 --> header_4</strong>
	<p></p>
</div>
 
<div class="test">
	<a name="header_2" id="header_2"></a>
	<strong onclick="javascript:scroller('header_5', 800);">header_2 --> header_5</strong>
	<p></p>
</div>
 
<div class="test">
	<a name="header_3" id="header_3"></a>
	<strong onclick="javascript:scroller('header_6', 800);">header_3 --> header_6</strong>
	<p></p>
</div>
 
<div class="test">
	<a name="header_4" id="header_4"></a>
	<strong onclick="javascript:scroller('header_7', 800);">header_4 --> header_7</strong>
	<p></p>
</div>
 
<div class="test">
	<a name="header_5" id="header_5"></a>
	<strong onclick="javascript:scroller('header_3', 800);">header_5 --> header_3</strong>
	<p></p>
</div>
 
<div class="test">
	<a name="header_6" id="header_6"></a>
	<strong onclick="javascript:scroller('header_2', 800);">header_6 --> header_2</strong>
	<p></p>
</div>
 
<div class="test">
	<a name="header_7" id="header_7"></a>
	<strong onclick="javascript:scroller('header_1', 800);">header_7 --> header_1</strong>
	<p></p>
</div>

用 Javascript 制作可暂停的滚动公告板

由标题很容易看出来,这是一个可以在显示每一个消息时都会暂停的动态滚动条,滚动条的样式完全由CSS控制,当然也包括显示尺寸。调整尺寸后就可以很容易的制作出一个单行的滚动公告板。

用 Javascript 制作可暂停的滚动公告板 – 示例

代码:

将以下代码放在网页的<head></head>之间。

 
<style type="text/css">

/*Example CSS for the two demo scrollers*/

#pscroller1{
width: 200px;
height: 100px;
border: 1px solid black;
padding: 5px;
background-color: lightyellow;
}

#pscroller2{
width: 450px;
height: 22px;
border: 1px solid black;
padding: 3px;
}

#pscroller2 a{
text-decoration: none;
}

.someclass{ //class to apply to your scroller(s) if desired
}

BODY, td, div {
FONT-SIZE: 12px; FONT-FAMILY: Verdana, Arial, Helvetica, sans-serif
}
A {
COLOR: #003499; TEXT-DECORATION: none; FONT-SIZE: 12px;
}
A:hover {
COLOR: #000000; TEXT-DECORATION: underline; FONT-SIZE: 12px;
}

</style>
 
<script type="text/javascript">

/*Example message arrays for the two demo scrollers*/

var pausecontent=new Array()
pausecontent[0]='<a href="http://YITU.org">艺图</a><br />欣赏高质量的国外艺术大师作品图片。欣赏经典名作,体味艺术人生。'
pausecontent[1]='<a href="http://www.codebit.cn">CodeBit.cn</a><br />收录经典小段代码,翻译转载国外优秀技术文章。'

var pausecontent2=new Array()
pausecontent2[0]='<a href="http://YITU.org">【艺图】 欣赏高质量的国外艺术大师作品图片。欣赏经典名作,体味艺术人生。</a>'
pausecontent2[1]='<a href="http://www.codebit.cn">【CodeBit.cn】 收录经典小段代码,翻译转载国外优秀技术文章。</a> '

</script>

<script type="text/javascript">

/***********************************************
* Pausing up-down scroller- ? Dynamic Drive (www.dynamicdrive.com)
* This notice MUST stay intact for legal use
* Visit http://www.dynamicdrive.com/ for this script and 100s more.
***********************************************/

function pausescroller(content, divId, divClass, delay){
	this.content=content //message array content
	this.tickerid=divId //ID of ticker div to display information
	this.delay=delay //Delay between msg change, in miliseconds.
	this.mouseoverBol=0 //Boolean to indicate whether mouse is currently over scroller (and pause it if it is)
	this.hiddendivpointer=1 //index of message array for hidden div
	document.write('<div id="'+divId+'" class="'+divClass+'" style="position: relative; overflow: hidden"><div class="innerDiv" style

="position: absolute; width: 100%" id="'+divId+'1">'+content[0]+'</div><div class="innerDiv" style="position: absolute; width: 100%; 

visibility: hidden" id="'+divId+'2">'+content[1]+'</div></div>')
	var scrollerinstance=this
	if (window.addEventListener) //run onload in DOM2 browsers
		window.addEventListener("load", function(){scrollerinstance.initialize()}, false)
	else if (window.attachEvent) //run onload in IE5.5+
		window.attachEvent("onload", function(){scrollerinstance.initialize()})
	else if (document.getElementById) //if legacy DOM browsers, just start scroller after 0.5 sec
	setTimeout(function(){scrollerinstance.initialize()}, 500)
}

// -------------------------------------------------------------------
// initialize()- Initialize scroller method.
// -Get div objects, set initial positions, start up down animation
// -------------------------------------------------------------------

pausescroller.prototype.initialize=function(){
	this.tickerdiv=document.getElementById(this.tickerid)
	this.visiblediv=document.getElementById(this.tickerid+"1")
	this.hiddendiv=this.hiddendiv=document.getElementById(this.tickerid+"2")
	this.visibledivtop=parseInt(pausescroller.getCSSpadding(this.tickerdiv))
	//set width of inner DIVs to outer DIV's width minus padding (padding assumed to be top padding x 2)
	this.visiblediv.style.width=this.hiddendiv.style.width=this.tickerdiv.offsetWidth-(this.visibledivtop*2)+"px"
	this.getinline(this.visiblediv, this.hiddendiv)
	this.hiddendiv.style.visibility="visible"
	var scrollerinstance=this
	this.tickerdiv.onmouseover=function(){scrollerinstance.mouseoverBol=1}
	this.tickerdiv.onmouseout=function(){scrollerinstance.mouseoverBol=0}
	setTimeout(function(){scrollerinstance.animateup()}, this.delay)
}


// -------------------------------------------------------------------
// animateup()- Move the two inner divs of the scroller up and in sync
// -------------------------------------------------------------------

pausescroller.prototype.animateup=function(){
	var scrollerinstance=this
	if (parseInt(this.hiddendiv.style.top)>(this.visibledivtop+5)){
		this.visiblediv.style.top=parseInt(this.visiblediv.style.top)-5+"px"
		this.hiddendiv.style.top=parseInt(this.hiddendiv.style.top)-5+"px"
		setTimeout(function(){scrollerinstance.animateup()}, 50)
	}else{
		this.getinline(this.hiddendiv, this.visiblediv)
		this.swapdivs()
		setTimeout(function(){scrollerinstance.setmessage()}, this.delay)
	}
}

// -------------------------------------------------------------------
// swapdivs()- Swap between which is the visible and which is the hidden div
// -------------------------------------------------------------------

pausescroller.prototype.swapdivs=function(){
	var tempcontainer=this.visiblediv
	this.visiblediv=this.hiddendiv
	this.hiddendiv=tempcontainer
}

pausescroller.prototype.getinline=function(div1, div2){
	div1.style.top=this.visibledivtop+"px"
	div2.style.top=Math.max(div1.parentNode.offsetHeight, div1.offsetHeight)+"px"
}

// -------------------------------------------------------------------
// setmessage()- Populate the hidden div with the next message before it's visible
// -------------------------------------------------------------------

pausescroller.prototype.setmessage=function(){
	var scrollerinstance=this
	if (this.mouseoverBol==1) //if mouse is currently over scoller, do nothing (pause it)
		setTimeout(function(){scrollerinstance.setmessage()}, 100)
	else{
		var i=this.hiddendivpointer
		var ceiling=this.content.length
		this.hiddendivpointer=(i+1>ceiling-1)? 0 : i+1
		this.hiddendiv.innerHTML=this.content[this.hiddendivpointer]
		this.animateup()
	}
}

pausescroller.getCSSpadding=function(tickerobj){ //get CSS padding value, if any
	if (tickerobj.currentStyle)
		return tickerobj.currentStyle["paddingTop"]
	else if (window.getComputedStyle) //if DOM2
		return window.getComputedStyle(tickerobj, "").getPropertyValue("padding-top")
	else
		return 0
}

</script>

然后将下面的代码插入到网页的<body></body>之间,可以放在你想显示的任意位置。

 
<script type="text/javascript">

//new pausescroller(name_of_message_array, CSS_ID, CSS_classname, pause_in_miliseconds)

new pausescroller(pausecontent, "pscroller1", "someclass", 3000)
document.write("<br />")
new pausescroller(pausecontent2, "pscroller2", "someclass", 2000)

</script>

调用说明:

new pausescroller(pausecontent, "pscroller1", "someclass", 3000)

其中 pausecontent 是你在<head></head>之间的代码定义的显示内容。pscroller1 是你在CSS中定义的唯一的滚动层ID, someclass 是任意您想附加的显示样式, 3000 是控制暂停的时间,以毫秒为单位。

控制显示样式的方法就是用标准的CSS语法:

 
#pscroller1{
width: 200px;
height: 100px;
border: 1px solid black;
padding: 5px;
background-color: lightyellow;
}

如果想创建单行的滚动条可以简单的将 height 值改为 20px 或是 25px 即可。

可暂停的滚动公告板,就这样完成了。