以更少的代码实现相同的效果应该是我们写程序的究极目标,当然可读性不能丢。在第一部分最后一个运行框,我已经做了这样的探索。不过换汤不换药,还是来来回回在scrollTop/scrollLeft与offsetTop/offsetLeft上做文章。总的思路基本是这样,让某个元素整体向某个方向移动,这样它里面的内容(图片或文字)就跟着移动,当元素移动到某一个距离后就回到原点。为了防止内容移着移着就没有了,我们需要两套相同的内容。在第一部分,第二套内容是动态生成的,并复制到另一个兄弟元素中,这在水平滚动时,我们需要花一些周折来让所有内容水平排列在一起。我就想,如果把第二套内容直接加在相同的元素是否效果会更好呢?起码CSS也少写一点。用scrollTop/scrollLeft实现滚动,还有一个缺点,它对父容器的宽度与高度有严格的规定的。比如我们想上下滚动图片,ul作为容器,li的图片为滚动内容,那么ul的高至少为图片的高的两倍(我们假设每张图片的尺寸都是相等的),否则就动不了。鉴此,我开发了新一代的无缝滚动函数。- <ul id="marquee">
- <li>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s017.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s018.jpg" alt="无缝滚动"/></a
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s019.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s020.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s021.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s022.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s023.jpg" alt="无缝滚动"/></a>
- </li>
- </ul>
复制代码 >- #marquee ,#marquee li {
- padding:0;
- margin:0;
- }
- #marquee {
- position:relative;
- list-style:none;
- height:150px;
- width:200px;
- overflow:hidden;
- border:10px solid #369;
- }
- #marquee li {
- position:absolute;
- }
- #marquee img {
- display:block;
- border:0;
- }
复制代码- var Marquee = function(id){
- try{document.execCommand("BackgroundImageCache", false, true);}catch(e){};
- var container = document.getElementById(id),
- slide = container.getElementsByTagName("li")[0],
- speed = arguments[1] || 10,
- delta = 0,//当前滚动的位置
- critical = slide.offsetHeight;//临界值
- slide.innerHTML += slide.innerHTML;
- var rolling = function(){
- delta == -critical ? delta = 0 : delta--;
- slide.style.top = delta + "px";
- }
- var timer = setInterval(rolling,speed)//设置定时器
- container.onmouseover=function() {clearInterval(timer)}//鼠标移到marquee上时,清除定时器,停止滚动
- container.onmouseout=function() {timer=setInterval(rolling,speed)}//鼠标移开时重设定时器
- }
- window.onload = function(){
- Marquee("marquee");
- }
复制代码-
- <!doctype html>
- <title>javascript无缝滚动 by 司徒正美</title>
- <meta charset="utf-8"/>
- <meta name="keywords" content="javascript无缝滚动 by 司徒正美" />
- <meta name="description" content="javascript无缝滚动 by 司徒正美" />
- <base href="http://images.cnblogs.com/cnblogs_com/rubylouvre/199042/">
- <style type="text/css">
- h1 {
- font:400 16px/1 "Microsoft YaHei",KaiTi_GB2312,SimSun
- }
- #marquee ,#marquee li {
- padding:0;
- margin:0;
- }
- #marquee {
- position:relative;
- list-style:none;
- height:150px;
- width:200px;
- overflow:hidden;
- border:10px solid #369;
- }
- #marquee li {
- position:absolute;
- }
- #marquee img {
- display:block;
- border:0;
- }
- </style>
- <script type="text/javascript">
- var Marquee = function(id){
- try{document.execCommand("BackgroundImageCache", false, true);}catch(e){};
- var container = document.getElementById(id),
- slide = container.getElementsByTagName("li")[0],
- speed = arguments[1] || 10,
- delta = 0,//当前滚动的位置
- critical = slide.offsetHeight;//临界点
- slide.innerHTML += slide.innerHTML;
- var rolling = function(){
- delta == -critical ? delta = 0 : delta--;
- slide.style.top = delta + "px";
- }
- var timer = setInterval(rolling,speed)//设置定时器
- container.onmouseover=function() {clearInterval(timer)}//鼠标移到marquee上时,清除定时器,停止滚动
- container.onmouseout=function() {timer=setInterval(rolling,speed)}//鼠标移开时重设定时器
- }
- window.onload = function(){
- Marquee("marquee");
- }
- </script>
- <h1>javascript无缝滚动(向上滚动) by 司徒正美</h1>
- <base href="http://images.cnblogs.com/cnblogs_com/rubylouvre/199042/">
- <ul id="marquee">
- <li>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s017.jpg" alt="无缝滚动 by 司徒正美"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s018.jpg" alt="无缝滚动 by 司徒正美"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s019.jpg" alt="无缝滚动 by 司徒正美"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s020.jpg" alt="无缝滚动 by 司徒正美"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s021.jpg" alt="无缝滚动 by 司徒正美"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s022.jpg" alt="无缝滚动 by 司徒正美"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s023.jpg" alt="无缝滚动 by 司徒正美"/></a>
- </li>
- </ul>
复制代码 向下滚动也很容易,只不过一开始把它定位到第一套内容与第二套内容之间,也就是slide.offsetHeight,不过我们需要把它改成负数让向整体向下移动,然后再慢慢向上移动。-
- <!doctype html>
- <title>javascript无缝滚动 by 司徒正美</title>
- <meta charset="utf-8"/>
- <meta name="keywords" content="javascript无缝滚动 by 司徒正美" />
- <meta name="description" content="javascript无缝滚动 by 司徒正美" />
- <base href="http://images.cnblogs.com/cnblogs_com/rubylouvre/199042/">
- <style type="text/css">
- h1 {
- font:400 16px/1 "Microsoft YaHei",KaiTi_GB2312,SimSun
- }
- #marquee ,#marquee li {
- padding:0;
- margin:0;
- }
- #marquee {
- position:relative;
- list-style:none;
- height:150px;
- width:200px;
- overflow:hidden;
- border:10px solid #B45B3E;
- }
- #marquee li {
- position:absolute;
- }
- #marquee img {
- display:block;
- border:0;
- }
- </style>
- <script type="text/javascript">
- var Marquee = function(id){
- try{document.execCommand("BackgroundImageCache", false, true);}catch(e){};
- var container = document.getElementById(id),
- slide = container.getElementsByTagName("li")[0],
- speed = arguments[1] || 10,
- critical = slide.offsetHeight,//临界值
- delta = -critical;
- slide.innerHTML += slide.innerHTML;
- var rolling = function(){
- delta == 0 ? delta = -critical : delta++;
- slide.style.top = delta + "px";
- }
- var timer = setInterval(rolling,speed)//设置定时器
- container.onmouseover=function() {clearInterval(timer)}//鼠标移到marquee上时,清除定时器,停止滚动
- container.onmouseout=function() {timer=setInterval(rolling,speed)}//鼠标移开时重设定时器
- }
- window.onload = function(){
- Marquee("marquee");
- }
- </script>
- <h1>javascript无缝滚动(向下滚动) by 司徒正美</h1>
- <base href="http://images.cnblogs.com/cnblogs_com/rubylouvre/199042/">
- <ul id="marquee">
- <li>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s017.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s018.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s019.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s020.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s021.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s022.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s023.jpg" alt="无缝滚动"/></a>
- </li>
- </ul>
复制代码 实现水平移动也比第一部分容易,结构层完全不用改动,表现层也改动很少。- #marquee ,#marquee li {
- padding:0;
- margin:0;
- }
- #marquee {
- position:relative;
- list-style:none;
- height:150px;
- width:200px;
- overflow:hidden;
- border:10px solid #B45B3E;
- }
- #marquee li {
- position:absolute;
- width:1000%;/*★★新增加★★*/
- }
- #marquee a {
- float:left;/*★★新增加★★*/
- }
- #marquee img {
- display:block;
- border:0;
- }
复制代码 难点是如何获取那个临界值,也就是夹在第一套内容与第二个套内容之间的那个位置。由于第二套内容我们并没有外套一个元素,因此我们需要从滚动对象下手。滚动对象都是a元素,我们需要计算出第二套内容的第一个a元素到达父元素左边的距离。这个值就是我们要求的临界值。明白这点,就轻松了。- //*************略*********
- slide.innerHTML += slide.innerHTML;
- var item = slide.getElementsByTagName("a"),
- critical = item[item.length/2].offsetLeft,//临界值
- //*************略*********
复制代码-
- <!doctype html>
- <title>javascript无缝滚动 by 司徒正美</title>
- <meta charset="utf-8"/>
- <meta name="keywords" content="javascript无缝滚动 by 司徒正美" />
- <meta name="description" content="javascript无缝滚动 by 司徒正美" />
- <base href="http://images.cnblogs.com/cnblogs_com/rubylouvre/199042/">
- <style type="text/css">
- h1 {
- font:400 16px/1 "Microsoft YaHei",KaiTi_GB2312,SimSun
- }
- #marquee ,#marquee li {
- padding:0;
- margin:0;
- }
- #marquee {
- position:relative;
- list-style:none;
- height:150px;
- width:200px;
- overflow:hidden;
- border:10px solid #8080C0;
- }
- #marquee li {
- position:absolute;
- width:1000%;/*新增加*/
- }
- #marquee a {
- float:left;/*新增加*/
- }
- #marquee img {
- display:block;
- border:0;
- }
- </style>
- <script type="text/javascript">
- var Marquee = function(id){
- try{document.execCommand("BackgroundImageCache", false, true);}catch(e){};
- var container = document.getElementById(id),
- slide = container.getElementsByTagName("li")[0],
- speed = arguments[1] || 10;
- slide.innerHTML += slide.innerHTML;
- var item = slide.getElementsByTagName("a"),
- critical = item[item.length/2].offsetLeft,//临界值
- delta = 0;
- var rolling = function(){
- delta == -critical ? delta = 0 : delta--;
- slide.style.left = delta + "px";
- }
- var timer = setInterval(rolling,speed)//设置定时器
- container.onmouseover=function() {clearInterval(timer)}//鼠标移到marquee上时,清除定时器,停止滚动
- container.onmouseout=function() {timer=setInterval(rolling,speed)}//鼠标移开时重设定时器
- }
- window.onload = function(){
- Marquee("marquee");
- }
- </script>
- <h1>javascript无缝滚动(向左滚动) by 司徒正美</h1>
- <base href="http://images.cnblogs.com/cnblogs_com/rubylouvre/199042/">
- <ul id="marquee">
- <li>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s017.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s018.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s019.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s020.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s021.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s022.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s023.jpg" alt="无缝滚动"/></a>
- </li>
- </ul>
复制代码 下面是向右滚动,由于都是不足20行的脚本,应该一看源码就明白,不详述了。-
- <!doctype html>
- <title>javascript无缝滚动 by 司徒正美</title>
- <meta charset="utf-8"/>
- <meta name="keywords" content="javascript无缝滚动 by 司徒正美" />
- <meta name="description" content="javascript无缝滚动 by 司徒正美" />
- <base href="http://images.cnblogs.com/cnblogs_com/rubylouvre/199042/">
- <style type="text/css">
- h1 {
- font:400 16px/1 "Microsoft YaHei",KaiTi_GB2312,SimSun
- }
- #marquee ,#marquee li {
- padding:0;
- margin:0;
- }
- #marquee {
- position:relative;
- list-style:none;
- height:150px;
- width:200px;
- overflow:hidden;
- border:10px solid #6cc;
- }
- #marquee li {
- position:absolute;
- width:1000%;
- }
- #marquee a {
- float:left;
- }
- #marquee img {
- display:block;
- border:0;
- }
- </style>
- <script type="text/javascript">
- var Marquee = function(id){
- try{document.execCommand("BackgroundImageCache", false, true);}catch(e){};
- var container = document.getElementById(id),
- slide = container.getElementsByTagName("li")[0],
- speed = arguments[1] || 10;
- slide.innerHTML += slide.innerHTML;
- var item = slide.getElementsByTagName("a"),//临界点
- critical = item[item.length/2].offsetLeft,
- delta = -critical;
- var rolling = function(){
- delta == 0 ? delta = -critical : delta++;
- slide.style.left = delta + "px";
- }
- var timer = setInterval(rolling,speed)//设置定时器
- container.onmouseover=function() {clearInterval(timer)}//鼠标移到marquee上时,清除定时器,停止滚动
- container.onmouseout=function() {timer=setInterval(rolling,speed)}//鼠标移开时重设定时器
- }
- window.onload = function(){
- Marquee("marquee");
- }
- </script>
- <h1>javascript无缝滚动(向右滚动) by 司徒正美</h1>
- <base href="http://images.cnblogs.com/cnblogs_com/rubylouvre/199042/">
- <ul id="marquee">
- <li>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s017.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s018.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s019.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s020.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s021.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s022.jpg" alt="无缝滚动"/></a>
- <a href="http://www.cnblogs.com/rubylouvre/"><img src="o_s023.jpg" alt="无缝滚动"/></a>
- </li>
- </ul>
复制代码 我们可以把上面四个函数合并成一个函数,结构层与表现层参照向上滚动。- var Marquee = function(id){
- try{document.execCommand("BackgroundImageCache", false, true);}catch(e){};
- var container = document.getElementById(id),
- slide = container.getElementsByTagName("li")[0],
- options = arguments[1] || {},
- speed = options.speed || 10,
- direction = options.direction || "left";
- slide.innerHTML += slide.innerHTML;
- var item = slide.getElementsByTagName("a"),
- critical,delta,rolling,field;
- if(direction == "left" || direction == "right"){
- slide.style.cssText = "width:1000%";
- for(var i=0 ,l=item.length; i<l;i++){
- item[i].style.cssText = "float:left";
- }
- field = "left";
- critical = item[item.length/2].offsetLeft;
- }else if(direction == "up" || direction == "down"){
- field = "top";
- critical = item[item.length/2].offsetTop;
- }
- if(direction == "up" || direction == "left"){
- delta = 0;
- rolling = function(){
- delta == -critical ? delta = 0 : delta--;
- slide.style[field] = delta + "px";
- }
- }else if(direction == "down" || direction == "right"){
- delta = -critical;
- rolling = function(){
- delta == 0 ? delta = -critical : delta++;
- slide.style[field] = delta + "px";
- }
- }
- var timer = setInterval(rolling,speed)//设置定时器
- container.onmouseover=function() {clearInterval(timer)}//鼠标移到marquee上时,清除定时器,停止滚动
- container.onmouseout=function() {timer=setInterval(rolling,speed)}//鼠标移开时重设定时器
- }
复制代码 使用:- Marquee("marquee",{speed:35,direction:"up"});
复制代码 |