现在的要求是C必须先于A、B节点之前，如何实现？
类似于下面的结构：
<div id="wrapper">
<div>C</div>
<div>A</div>
<div>B</div>
</div>
请思考……..
我的解答：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title> new document </title>
<meta name="generator" content="editplus" />
<meta name="author" content="" />
<meta name="keywords" content="" />
<meta name="description" content="" />
<meta http-equiv='content-type' content='text/html;charset=utf-8' />
<style type='text/css'>
* {margin:0; padding:0;}
body {background-color:#fff;}
#wrapper {400px;margin:100px; border:1px solid #ff0000;}
#wrapper:after {content:"."; height:0; line-height:0; visibility:hidden; overflow:hidden; display:block; clear:both;}
#content,#secondPrimary,#extra{background-color:#CDD8DA; text-align:center; position:relative;}
#primary {100%; float:right; margin-left:-200px;}
#content {margin-left:210px; height:500px; line-height:500px;}
#secondPrimary {float:left; 200px; height:300px; line-height:300px;}
#extra {clear:float; float:left; height:190px; 200px; margin-top:10px; line-height:190px;}
.current {background-color:#DDF8C0; position:absolute; top:0; left:0;}
</style>
</head>
<body>
<div id="wrapper">
<div id="primary">
<div id='content'>
<div>C</div>
</div>
</div>
<div id="secondPrimary">
<div>A</div>
</div>
<div id="extra">
<div>B</div>
</div>
</div>
<script type="text/javascript">
function $(id) {
return typeof id === 'string' ? document.getElementById(id) : id;
}
var Event = {
add : function(el, handler, fn) {
handler = handler.replace(/^on/, "").toLowerCase();
if(el.attachEvent) {
el.attachEvent("on" + handler, fn);
} else {
el.addEventListener(handler, fn, false);
}
return el;
},
remove : function(el, handler, fn) {
handler = handler.replace(/^on/, "").toLowerCase();
if(el.detachEvent) {
el.detachEvent("on" + handler, fn);
} else {
el.removeEventListener(handler, fn, false);
}
return el;
},
removeAll : function() {
}
};
var Dom = {
getParent : function(node) {
if(!node) {
return null;
}
var parent = !!node.parentNode && node.parentNode.nodeType == 1 ? node.parentNode : null;
if(!parent) {
while (parent) {
parent = parent.parentNode;
if(!!parent && parent.nodeType == 1) {
break;
}
}
}
return parent;
},
getFirstChild : function(node) {
if (!node) {
return null;
}
var child = !!node.firstChild && node.firstChild.nodeType == 1 ? node.firstChild : null;
return child || this.getNextSibling(node.firstChild);
},
getNextSibling : function(node) {
if(!node) {
return null;
}
while (node) {
node = node.nextSibling;
if(!!node && node.nodeType == 1) {
return node;
}
}
return null;
},
/**
* 判断指定的节点是否是第二个节点的祖先
*/
isAncestor : function(node1, node2) {
if(!node1 || !node2) {
return false;
}
return node1.contains ? (node1 != node2 && node1.contains(node2)) : !!(node1.compareDocumentPosition(node2) & 16);
}
}
function zoomIn(ev, rate) {
if (!this._w) {
this._w = this._w || this.offsetWidth;
this._h = this._h || this.offsetHeight;
}
this.style.zIndex = 1;
var child = Dom.getFirstChild(this);
child.className = "current";
child.style.width = this.offsetWidth * rate + "px";
child.style.height = this.offsetHeight * rate + "px";
child.style.lineHeight = this.offsetHeight * rate + "px";
}
function zoomOut(ev, rate) {
this.style.zIndex = 0;
var child = Dom.getFirstChild(this);
child.className = "";
child.style.width = '100%';
child.style.height = '100%';
child.style.lineHeight = this._h + 'px';
}
!(function() {
var a = $("content"), b = $("secondPrimary"), c = $("extra");
var arr = [a, b, c], tempEl = null, zoomRate = 1.2;
for (var i = 0,len = arr.length; i<len;i++) {
tempEl = arr[i];
//绑定mouseover事件
Event.add(tempEl, 'mouseover', function(el, rate) {
return function() {
var args = Array.prototype.slice.call(arguments).concat([rate]);
return zoomIn.apply(el, args);
}
}(tempEl, zoomRate));
//绑定mouseout事件
Event.add(tempEl, 'mouseout', function(el, rate) {
return function() {
var args = Array.prototype.slice.call(arguments).concat([rate]);
return zoomOut.apply(el, args);
}
}(tempEl, zoomRate));
}
a = b = c = arr = tempEl = zoomRate = null;
})();
</script>
</body>
</html>
运行实例，查看效果：