CSS的相关操作，获取完整样式。 其中将100%，1em等相对单位换成精确PX代码值得一看 完整代码在：https://github.com/RubyLouvre/avalon/blob/master/avalon.js

csshooks.js

//=============================css相关=======================
var cssHooks = avalon.cssHooks = {}
var prefixes = ['', '-webkit-', '-o-', '-moz-', '-ms-']
var cssMap = {
    "float": 'cssFloat' in root.style ? 'cssFloat' : 'styleFloat',
    background: "backgroundColor"
}
var cssNumber = oneObject("columnCount,order,fillOpacity,fontWeight,lineHeight,opacity,orphans,widows,zIndex,zoom")

function cssName(name, host, camelCase) {
    if (cssMap[name]) {
        return cssMap[name]
    }
    host = host || root.style
    for (var i = 0, n = prefixes.length; i < n; i++) {
        camelCase = camelize(prefixes[i] + name)
        if (camelCase in host) {
            return (cssMap[name] = camelCase)
        }
    }
    return null
}
cssHooks["@:set"] = function(node, name, value) {
    try { //node.style.width = NaN;node.style.width = "xxxxxxx";node.style.width = undefine 在旧式IE下会抛异常
        node.style[name] = value
    } catch (e) {
    }
}
if (window.getComputedStyle) {
    cssHooks["@:get"] = function(node, name) {
        var ret, styles = window.getComputedStyle(node, null)
        if (styles) {
            ret = name === "filter" ? styles.getPropertyValue(name) : styles[name]
            if (ret === "") {
                ret = node.style[name] //其他浏览器需要我们手动取内联样式
            }
        }
        return ret
    }
    cssHooks["opacity:get"] = function(node) {
        var ret = cssHooks["@:get"](node, "opacity")
        return ret === "" ? "1" : ret
    }
} else {
    var rnumnonpx = /^-?(?:\d*\.)?\d+(?!px)[^\d\s]+$/i
    var rposition = /^(top|right|bottom|left)$/
    var ie8 = !!window.XDomainRequest
    var salpha = "DXImageTransform.Microsoft.Alpha"
    var border = {
        thin: ie8 ? '1px' : '2px',
        medium: ie8 ? '3px' : '4px',
        thick: ie8 ? '5px' : '6px'
    }
    cssHooks["@:get"] = function(node, name) {
        //取得精确值，不过它有可能是带em,pc,mm,pt,%等单位
        var currentStyle = node.currentStyle
        var ret = currentStyle[name]
        if ((rnumnonpx.test(ret) && !rposition.test(ret))) {
            //①，保存原有的style.left, runtimeStyle.left,
            var style = node.style,
                    left = style.left,
                    rsLeft = node.runtimeStyle.left
            //②由于③处的style.left = xxx会影响到currentStyle.left，
            //因此把它currentStyle.left放到runtimeStyle.left，
            //runtimeStyle.left拥有最高优先级，不会style.left影响
            node.runtimeStyle.left = currentStyle.left
            //③将精确值赋给到style.left，然后通过IE的另一个私有属性 style.pixelLeft
            //得到单位为px的结果；fontSize的分支见http://bugs.jquery.com/ticket/760
            style.left = name === 'fontSize' ? '1em' : (ret || 0)
            ret = style.pixelLeft + "px"
            //④还原 style.left，runtimeStyle.left
            style.left = left
            node.runtimeStyle.left = rsLeft
        }
        if (ret === "medium") {
            name = name.replace("Width", "Style")
            //border width 默认值为medium，即使其为0"
            if (currentStyle[name] === "none") {
                ret = "0px"
            }
        }
        return ret === "" ? "auto" : border[ret] || ret
    }
    cssHooks["opacity:set"] = function(node, name, value) {
        node.style.filter = 'alpha(opacity=' + value * 100 + ')'
        node.style.zoom = 1
    }
    cssHooks["opacity:get"] = function(node) {
        //这是最快的获取IE透明值的方式，不需要动用正则了！
        var alpha = node.filters.alpha || node.filters[salpha],
                op = alpha ? alpha.opacity : 100
        return (op / 100) + "" //确保返回的是字符串
    }
}

"top,left".replace(rword, function(name) {
    cssHooks[name + ":get"] = function(node) {
        var computed = cssHooks["@:get"](node, name)
        return /px$/.test(computed) ? computed :
                avalon(node).position()[ name ] + "px"
    }
})
"Width,Height".replace(rword, function(name) {
    var method = name.toLowerCase(),
            clientProp = "client" + name,
            scrollProp = "scroll" + name,
            offsetProp = "offset" + name
    avalon.fn[method] = function(value) {
        var node = this[0]
        if (arguments.length === 0) {
            if (node.setTimeout) { //取得窗口尺寸,IE9后可以用node.innerWidth /innerHeight代替
                return node["inner" + name] || node.document.documentElement[clientProp]
            }
            if (node.nodeType === 9) { //取得页面尺寸
                var doc = node.documentElement
                //FF chrome    html.scrollHeight< body.scrollHeight
                //IE 标准模式 : html.scrollHeight> body.scrollHeight
                //IE 怪异模式 : html.scrollHeight 最大等于可视窗口多一点？
                return Math.max(node.body[scrollProp], doc[scrollProp], node.body[offsetProp], doc[offsetProp], doc[clientProp])
            }
            return parseFloat(this.css(method)) || 0
        } else {
            return this.css(method, value)
        }
    }
})