| 編程（Programming）是編定程序的中文簡(jiǎn)稱，就是讓計(jì)算機(jī)代碼解決某個(gè)問(wèn)題，對(duì)某個(gè)計(jì)算體系規(guī)定一定的運(yùn)算方式，使計(jì)算體系按照該計(jì)算方式運(yùn)行，并最終得到相應(yīng)結(jié)果的過(guò)程。為了使計(jì)算機(jī)能夠理解（understand）人的意圖，人類就必須將需解決的問(wèn)題的思路、方法和手段通過(guò)計(jì)算機(jī)能夠理解的形式告訴計(jì)算機(jī)，使得計(jì)算機(jī)能夠根據(jù)人的指令一步一步去工作，完成某種特定的任務(wù)。這種人和計(jì)算體系之間交流的過(guò)程就是編程。 【實(shí)例名稱】 JS實(shí)現(xiàn)圖片新聞切換效果 【實(shí)例描述】 新聞切換技術(shù)想必大家都很熟悉，本例研究其切換效果如何實(shí)現(xiàn)。 【實(shí)例代碼】 <html>
<head>
<style type="text/css">
body { text-align: center; margin:0; padding:0;
background: #FFF; font-size:12px; color:#000;}
div,form,img,ul,ol,li,dl,dt,dd
{margin: 0; padding: 0; border: 0;}
h1,h2,h3,h4,h5,h6 { margin:0; padding:0;}
table,td,tr,th{font-size:12px;}
a:link {color: #000; text-decoration:none;}
a:visited {color: #83006f;text-decoration:none;}
a:hover {color: #c00; text-decoration:underline;}
a:active {color: #000;}
.focusPic{margin:0 auto; width:244px;}
.focusPic .pic{margin:0 auto; width:240px;
height:180px; padding:2px 0 0;}
.focusPic .adPic{margin:0 auto 5px; width:240px; height:29px;
overflow:hidden;background:url(http://tech.163.com/newimg/adpic.gif);}
.focusPic .adPic .text{float:right; padding:9px 4px 0 0; width:140px;}
.focusPic .adPic .text a{color:#1f3a87;}
.focusPic .adPic .text a:hover{color:#bc2931;}
.focusPic h2{ float:left; width:232px;padding:4px 0 3px 12px;
font-size:14px; text-align:left;}
.focusPic p{float:left; width:226px;line-height:160%;
margin:0; text-align:left;padding:0 0 10px 12px;}
.focusPic p img {margin:0px 0 2px;}
.focusPic .more{ margin:0 auto; width:240px; }
.focusPic .more .textNum{float:right;
margin:0 8px 0 0;padding:0 0 4px;}
.focusPic .more .textNum .text{float:left;
font-weight:bold; padding:7px 6px 0 0; color:#666;}
.focusPic .more .textNum .num{float:left; width:113px; height:19px;}
.focusPic .more .textNum .bg1{ background:url(http://tech.163.com/newimg/num1.gif);}
.focusPic .more .textNum .bg2{ background:url(http://tech.163.com//num2.gif);}
.focusPic .more .textNum .bg3{ background:url(http://tech.163.com/newimg/num3.gif);}
.focusPic .more .textNum .bg4{ background:url(http://tech.163.com/newimg/num4.gif);}
.focusPic .more .textNum .num ul{ float:left; width:113px;}
.focusPic .more .textNum .num li{float:left; width:28px;
font-weight:bold;display:block; color:#fff; list-style-type:none; padding:6px 0 0;}
.focusPic .more .textNum .num li a{color:#fff; padding:0 5px; }
.focusPic .more .textNum .num li a:visited{color:#fff;}
.focusPic .more .textNum .num li a:hover{color:#ff0;}
</style>
<script language="JavaScript" type="text/javascript">
var nn;
nn=1;
setTimeout('change_img()',6000);
function change_img()
{
if(nn>4) nn=1
setTimeout('setFocus1('+nn+')',6000);
nn++;
tt=setTimeout('change_img()',6000);
}
function setFocus1(i)
{
selectLayer1(i);
}
function selectLayer1(i)
{
switch(i)
{
case 1:
document.getElementById("focusPic1").style.display="block";
document.getElementById("focusPic2").style.display="none";
document.getElementById("focusPic3").style.display="none";
document.getElementById("focusPic4").style.display="none";
document.getElementById("focusPic1nav").style.display="block";
document.getElementById("focusPic2nav").style.display="none";
document.getElementById("focusPic3nav").style.display="none";
document.getElementById("focusPic4nav").style.display="none";
break;
case 2:
document.getElementById("focusPic1").style.display="none";
document.getElementById("focusPic2").style.display="block";
document.getElementById("focusPic3").style.display="none";
document.getElementById("focusPic4").style.display="none";
document.getElementById("focusPic1nav").style.display="none";
document.getElementById("focusPic2nav").style.display="block";
document.getElementById("focusPic3nav").style.display="none";
document.getElementById("focusPic4nav").style.display="none";
break;
case 3:
document.getElementById("focusPic1").style.display="none";
document.getElementById("focusPic2").style.display="none";
document.getElementById("focusPic3").style.display="block";
document.getElementById("focusPic4").style.display="none";
document.getElementById("focusPic1nav").style.display="none";
document.getElementById("focusPic2nav").style.display="none";
document.getElementById("focusPic3nav").style.display="block";
document.getElementById("focusPic4nav").style.display="none";
break;
case 4:
document.getElementById("focusPic1").style.display="none";
document.getElementById("focusPic2").style.display="none";
document.getElementById("focusPic3").style.display="none";
document.getElementById("focusPic4").style.display="block";
document.getElementById("focusPic1nav").style.display="none";
document.getElementById("focusPic2nav").style.display="none";
document.getElementById("focusPic3nav").style.display="none";
document.getElementById("focusPic4nav").style.display="block";
break;
}
}
</script>
</head> <body>
<div class="focusPic">
<div id="focusPic1" style="display:block ;">
<div class="pic"> <a href="http://tech.163.com/11/0411/05/71BB3NO0000915BF.html">
<img src=http://img3.cache.netease.com/tech/2011/4/11/2011041105573667bd5.jpg
alt="Facebook或年內(nèi)曲線入華" width="240" height="180" border="0" /></a> </div>
<h2><a href="http://tech.163.com/11/0411/05/71BB3NO0000915BF.html">
Facebook或年內(nèi)曲線入華</a></h2>
<p>有分析稱，F(xiàn)acebook入華不外乎兩條途徑：一是成立合資公司，二是合作、收購(gòu)。點(diǎn)擊進(jìn)入查看……
<img src="/newimg/i2.gif" alt="詳細(xì)" width="3" height="5" />
<a href=http://tech.163.com/11/0411/05/71BB3NO0000915BF.html
class="cDRed">詳細(xì)</a></p>
</div>
<div id="focusPic2" style="display: none ;">
<div class="pic"> <a href="http://tech.163.com/discover/">
<img src=http://cimg.163.com/tech/2006/1/17/200601171557008cee7.jpg
alt="顛覆叢林動(dòng)物生存法則" width="240" height="180" border="0" /></a> </div>
<h2><a href="http://tech.163.com/discover/">顛覆叢林動(dòng)物生存法則</a></h2>
<p>群居動(dòng)物的這種行為顛覆了我們通常認(rèn)為的，在動(dòng)物世界通行的 “叢林法則”，
動(dòng)物不都自私，不都是弱肉強(qiáng)食的。<img src="/newimg/i2.gif" alt="詳細(xì)"
width="3" height="5" /> <a href="http://tech.163.com/discover/" class="cDRed">
詳細(xì)</a></p>
</div>
<div id="focusPic3" style="display: none ;">
<div class="pic"> <a href="http://tech.163.com/special/00091MNJ/itobserve015.html">
<img src="http://cimg.163.com/tech/2006/1/17/2006011711483290a60.jpg" alt="WAPI并非貿(mào)易陰謀"
width="240" height="180" border="0" /></a> </div>
<h2><a href="http://tech.163.com/special/00091MNJ/itobserve015.html">WAPI并非貿(mào)易陰謀</a>
</h2>
<p>近日國(guó)家做出決定：“將向其他的國(guó)內(nèi)及國(guó)外企業(yè)公布該算法”。事實(shí)證明中國(guó)WAPI標(biāo)準(zhǔn)并非是貿(mào)易陰謀。
<img src="/newimg/i2.gif" alt="詳細(xì)" width="3" height="5" />
<a href="http://tech.163.com/special/00091MNJ/itobserve015.html" class="cDRed">
詳細(xì)</a></p>
</div>
<div id="focusPic4" style="display: none ;">
<div class="pic"> <a href="http://tech.163.com/special/00091OSI/horizons.html">
<img src=http://cimg.163.com/tech/2006/1/17/200601171002503f251.jpg
alt="新視野號(hào)探測(cè)冥王星特別專題" width="240" height="180" border="0" /></a> </div>
<h2><a href="http://tech.163.com/special/00091OSI/horizons.html">
新視野號(hào)探測(cè)冥王星特別專題</a></h2>
<p>美國(guó)宇航局將于北京時(shí)間18日凌晨2時(shí)24分發(fā)射新視野號(hào)探測(cè)器，
造訪這顆人類唯一尚未探測(cè)過(guò)的行星-冥王星。<img src="/newimg/i2.gif" alt="詳細(xì)"
width="3" height="5" /> <a href=http://tech.163.com/special/00091OSI/horizons.html
class="cDRed">詳細(xì)</a></p>
</div>
<div class="more">
<div class="textNum">
<div class="text">> 更多頭圖新聞</div>
<div class="num bg1" id="focusPic1nav" style="display: block;">
<ul>
<li>1</li>
<li><a href="javascript:setFocus1(2);" target="_self">2</a></li>
<li><a href="javascript:setFocus1(3);" target="_self">3</a></li>
<li><a href="javascript:setFocus1(4);" target="_self">4</a></li>
</ul>
</div>
<div class="num bg2" id="focusPic2nav" style="display: none;">
<ul>
<li><a href="javascript:setFocus1(1);" target="_self">1</a></li>
<li>2</li>
<li><a href="javascript:setFocus1(3);" target="_self">3</a></li>
<li><a href="javascript:setFocus1(4);" target="_self">4</a></li>
</ul>
</div>
<div class="num bg3" id="focusPic3nav" style="display: none;">
<ul>
<li><a href="javascript:setFocus1(1);" target="_self">1</a></li>
<li><a href="javascript:setFocus1(2);" target="_self">2</a></li>
<li>3</li>
<li><a href="javascript:setFocus1(4);" target="_self">4</a></li>
</ul>
</div>
<div class="num bg4" id="focusPic4nav" style="display: none;">
<ul>
<li><a href="javascript:setFocus1(1);" target="_self">1</a></li>
<li><a href="javascript:setFocus1(2);" target="_self">2</a></li>
<li><a href="javascript:setFocus1(3);" target="_self">3</a></li>
<li>4</li>
</ul>
</div>
</div>
</div>
</div> </body>
</html>
需要在bodyr中添加一些新聞，注意這些新聞的布局。
【運(yùn)行效果】  【難點(diǎn)剖析】 本例的重點(diǎn)是頁(yè)面的布局和控件的樣式。其中要注意獲取頁(yè)面元素使用的是“document．getElementById()”方法，其中的參數(shù)就是要獲取的元素id。修改元素的樣式使用“style”屬性，其中“style．display”用來(lái)控制元素的顯示和隱藏。 【源碼下載】 為了JS代碼的準(zhǔn)確性，請(qǐng)點(diǎn)擊：JS實(shí)現(xiàn)圖片新聞切換效果 進(jìn)行本實(shí)例源碼下載
使用編程語(yǔ)言寫的程序，由于每條指令都對(duì)應(yīng)計(jì)算機(jī)一個(gè)特定的基本動(dòng)作，所以程序占用內(nèi)存少、執(zhí)行效率高。
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