总结:
<a href="javascript:;"/>，其中javascript:是伪协议，它可以让我们通过一个链接来调用javascript函数.而采用这个方式 javascript:;可以实现A标签的点击事件运行时，如果页面内容很多，有滚动条时，页面不会乱跳，用户体验更好。
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<style>
p { margin:0; }
body { text-align:center; }
#box { 400px; height:400px; border:10px solid #ccc; margin:50px auto 0; position:relative; }
a { 40px; height:40px; background:#fff; filter:alpha(opacity:80); opacity:0.8; position:absolute; top:160px; font-size:18px; color:#000; text-align:center; line-height:40px; text-decoration:none; }
a:hover { filter:alpha(opacity:30); opacity:0.3; }
#prev { left:10px; }
#next { right:10px; }
#p1 { 400px; height:30px; line-height:30px; text-align:center; background:#000; color:#fff; font-size:14px; filter:alpha(opacity:80); opacity:0.8; position:absolute; bottom:0; left:0; }
strong { 400px; height:30px; line-height:30px; text-align:center; background:#000; color:#fff; font-size:14px; filter:alpha(opacity:80); opacity:0.8; position:absolute; top:0; left:0; }
#img1 { 400px; height:400px; }
span { position:absolute; 400px; height:30px; line-height:30px; text-align:center; top:-50px; left:0; font-family:'微软雅黑'; }
</style>
<script>
window.onload = function (){
var oPrev = document.getElementById('prev');
var oNext = document.getElementById('next');
var oP = document.getElementById('p1');
var oStrong = document.getElementById('strong1');
var oImg = document.getElementById('img1');
var aBtn = document.getElementsByTagName('input');
var arrUrl = [ 'images/1.jpg', 'images/2.jpg', 'images/3.jpg', 'images/4.jpg' ];//以后用ajax从服务端拿到数据
var arrText = [ '文字一', '文字二', '文字三', '识文断字' ];////以后用ajax从服务端拿到数据
var num = 0;
var onOff = true;//true 为循环播放 false为顺序播放
aBtn[0].onclick = function (){ onOff = true; document.getElementsByTagName('span')[0].innerHTML = '循环切换'; };
aBtn[1].onclick = function (){ onOff = false; document.getElementsByTagName('span')[0].innerHTML = '顺序切换'; };
// 初始化
function fnTab(){
oP.innerHTML = arrText[num];
oStrong.innerHTML = num+1 + ' / ' + arrText.length;
oImg.src = arrUrl[num];
}
fnTab();
oPrev.onclick = function (){
num --;
if( num == -1 ){
if(onOff){
num = arrText.length-1;
}
else{
alert('这已经是第一张了，不能再往前了~~');
num = 0;
}
}
fnTab();
};
oNext.onclick = function (){
num ++;
if( num == arrText.length ){
if(onOff){
num = 0;
}else{
alert('已经到最后一张啦~');
num = arrText.length-1;
}
}
fnTab();
};
};
</script>
</head>
<body>
<input type="button" value="循环切换" />
<input type="button" value="顺序切换" />
<div id="box"><span>图片可从最后一张跳转到第一张循环切换</span>
<a id="prev" href="javascript:;"><</a>
<a id="next" href="javascript:;">></a>
<p id="p1">图片文字加载中……</p>
<strong id="strong1">图片数量计算中……</strong>
<img id="img1" />
</div>
</body>
</html>