架构（HTML）样式（CSS）行为（JavaScript）三者分离
三者分离有什么好处我就不说了，直接上代码，有不甚解的地方，评论里咨询，好了，直接上代码：
TEST.html
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title>JPG</title>
<meta charset="utf-8" />
<link rel="stylesheet" href="StyleSheet.css" media="screen"/>
</head>
<body>
<h1>Snapshots</h1>
<ul id="imagegallery">
<li>
<a href="jpg/1.jpg" title="onePic" >可爱</a>
</li>
<li>
<a href="jpg/2.jpg" title="twoPic" >活泼</a>
</li>
<li>
<a href="jpg/3.jpg" title="threePic" >清纯</a>
</li>
<li>
<a href="jpg/4.jpg" title="fourPic" >性感</a>
</li>
</ul>
<script src="example.js"></script>
</body>
</html>
StyleSheet.css
body {
font-family: "Helvetica","Arial",serif;
color: #333;
background-color: #ccc;
margin: 1em 10%;
}
h1 {
color: #333;
background-color: transparent;
}
a {
color: #c60;
background-color: transparent;
font-weight: bold;
text-decoration: none;
}
ul {
padding: 0;
}
li {
float: left;
padding: 1em;
list-style: none;
}
#imagegallery {
list-style: none;
}
#imagegallery li {
display: inline;
}
#imagegallery li a img {
border: 0;
}
example.js
function preparePlaceholder() {
if (!document.createElement) return false;
if (!document.createTextNode) return false;
if (!document.getElementById) return false;
if (!document.getElementById("imagegallery")) return false;
var placeholder = document.createElement("img");
placeholder.setAttribute("id", "placeholder")
placeholder.setAttribute("src", "jpg/5.jpg");
placeholder.setAttribute("alt", "my image gallery");
var description = document.createElement("p");
description.setAttribute("id", "description");
var desctext = document.createTextNode("Choose an image");
description.appendChild(desctext);
var gallery = document.getElementById("imagegallery")
insertAfter(placeholder, gallery);
insertAfter(description, placeholder);
}
function prepareGallery() {
if (!document.getElementsByTagName) return false;
if (!document.getElementById) return false;
if (!document.getElementById("imagegallery")) return false;
var gallery = document.getElementById("imagegallery");
var links = gallery.getElementsByTagName("a");
for (var i = 0; i < links.length; i++) {
links[i].onclick = function () {
return showPic(this);
}
links[i].onkeypress = links[i].onclick;
}
}
function showPic(whichpic) {
if (!document.getElementById("placeholder")) return false;
var source = whichpic.getAttribute("href");
var placeholder = document.getElementById("placeholder");
if (placeholder.nodeName != "IMG") return false;
placeholder.setAttribute("src", source);
if (document.getElementById("description")) {
var text = whichpic.getAttribute("title") ? whichpic.getAttribute("title") : "";
var description = document.getElementById("description");
if (description.firstChild.nodeType == 3) {
description.firstChild.nodeValue = text;
}
}
return false;
}
addLoadEvent(preparePlaceholder);
addLoadEvent(prepareGallery);