javascript 精确获取样式属性（下）_javascript技巧

复制代码 代码如下:

var rgb2hex = function(rgb) {
rgb = rgb.match(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/);
return "#"+tohex(rgb[1])+tohex(rgb[2])+tohex(rgb[3])
}
var tohex = function(x) {
var hexDigits = ['0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'];
return isNaN(x) ? '00' : hexDigits[(x - x % 16) / 16] + hexDigits[x % 16];
}

我们用正则表达式在检测其是否为rgb格式，是就用rgb2hex来转换它。但如果是red，green等值呢，火狐就一反常态，转换为hex格式，但IE依然如故。我们没有办法，自己做一个哈希，把常用的颜色都弄进去，然后一一匹对便是。

复制代码 代码如下:

if(style.search(/background|color/) != -1) {
var color = {
aqua: '#0ff',
black: '#000',
blue: '#00f',
gray: '#808080',
purple: '#800080',
fuchsia: '#f0f',
green: '#008000',
lime: '#0f0',
maroon: '#800000',
navy: '#000080',
olive: '#808000',
orange:'#ffa500',
red: '#f00',
silver: '#c0c0c0',
teal: '#008080',
transparent:'rgba(0,0,0,0)',
white: '#fff',
yellow: '#ff0'
}
if(!!color[value]){
value = color[value]
}
if(value == "inherit"){
return getStyle(el.parentNode,style);
}
if(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/.test(value)){
return rgb2hex(value)
}else if(/^#/.test(value)){
value = value.replace('#', '');
return "#" + (value.length == 3 ? value.replace(/^(\w)(\w)(\w)$/, '$1$1$2$2$3$3') : value);
}
return value;
}

基本上是对于CSS的精确取值就是这样，显然它还存在许多不足之处，但对于布局用的和常用的样式都实现了。还提供了一个判断页面渲染模式的常数q，为了方便，方法名与JQuery同名（只能取值，不能赋值，以后有空慢慢与我的addSheet函数整合到一起）。

复制代码 代码如下:

(function(){
var isQuirk = (document.documentMode) ? (document.documentMode==5) ? true : false : ((document.compatMode=="CSS1Compat") ? false : true);
var isElement = function(el) {
return !!(el && el.nodeType == 1);
}
var propCache = [];
var propFloat = !+"\v1" ? 'styleFloat' : 'cssFloat';
var camelize = function(attr){
return attr.replace(/\-(\w)/g, function(all, letter){
return letter.toUpperCase();
});
}
var memorize = function(prop) { //意思为：check out form cache
return propCache[prop] || (propCache[prop] = prop == 'float' ? propFloat : camelize(prop));
}
var getIEOpacity = function(el){
var filter;
if(!!window.XDomainRequest){
filter = el.style.filter.match(/progid:DXImageTransform.Microsoft.Alpha\(.?opacity=(.*).?\)/i);
}else{
filter = el.style.filter.match(/alpha\(opacity=(.*)\)/i);
}
if(filter){
var value = parseFloat(filter[1]);
if (!isNaN(value)) {
return value ? value / 100 : 0;
}
}
return 1;
}
var convertPixelValue = function(el, value){
var style = el.style,left = style.left,rsLeft = el.runtimeStyle.left;
el.runtimeStyle.left = el.currentStyle.left;
style.left = value || 0;
var px = style.pixelLeft;
style.left = left;//还原数据
el.runtimeStyle.left = rsLeft;//还原数据
return px + "px"
}
var rgb2hex = function(rgb) {
rgb = rgb.match(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/);
return "#"+tohex(rgb[1])+tohex(rgb[2])+tohex(rgb[3])
}
var tohex = function(x) {
var hexDigits = ['0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'];
return isNaN(x) ? '00' : hexDigits[(x - x % 16) / 16] + hexDigits[x % 16];
}
var getStyle = function (el, style){
var value;
if(!+"\v1"){
//特殊处理IE的opacity
if(style == "opacity"){
return getIEOpacity(el)
}
value = el.currentStyle[memorize(style)];
//特殊处理IE的height与width
if (/^(height|width)$/.test(style)){
var values = (style == 'width') ? ['left', 'right'] : ['top', 'bottom'], size = 0;
if(isQuirk){
return el[camelize("offset-"+style)] + "px"
}else{
var client = parseFloat(el[camelize("client-"+style)]),
paddingA = parseFloat(getStyle(el, "padding-"+ values[0])),
paddingB = parseFloat(getStyle(el, "padding-"+ values[1]));
return (client - paddingA - paddingB)+"px";
}
}
}else{
if(style == "float"){
style = propFloat;
}
value = document.defaultView.getComputedStyle(el, null).getPropertyValue(style)
}
//下面部分全部用来转换上面得出的非精确值
if(!/^\d+px$/.test(value)){
//转换可度量的值
if(/(em|pt|mm|cm|pc|in|ex|rem|vw|vh|vm|ch|gr)$/.test(value)){
return convertPixelValue(el,value);
}
//转换百分比，不包括字体
if(/%$/.test(value) && style != "font-size"){
return parseFloat(getStyle(el.parentNode,"width")) * parseFloat(value) /100 + "px"
}
//转换border的thin medium thick
if(/^(border).+(width)$/.test(style)){
var s = style.replace("width","style"),
b = {
thin:["1px","2px"],
medium:["3px","4px"],
thick:["5px","6px"]
};
if(value == "medium" && getStyle(el,s) == "none"){
return "0px";
}
return !!window.XDomainRequest ? b[value][0] : b[value][1];
}
//转换margin的auto
if(/^(margin).+/.test(style) && value == "auto"){
var father = el.parentNode;
if(/MSIE 6/.test(navigator.userAgent) && getStyle(father,"text-align") == "center"){
var fatherWidth = parseFloat(getStyle(father,"width")),
_temp = getStyle(father,"position");
father.runtimeStyle.postion = "relative";
var offsetWidth = el.offsetWidth;
father.runtimeStyle.postion = _temp;
return (fatherWidth - offsetWidth)/2 + "px";
}
return "0px";
}
//转换top|left|right|bottom的auto
if(/(top|left|right|bottom)/.test(style) && value == "auto"){
return el.getBoundingClientRect()[style];
}
//转换颜色
if(style.search(/background|color/) != -1) {
var color = {
aqua: '#0ff',
black: '#000',
blue: '#00f',
gray: '#808080',
purple: '#800080',
fuchsia: '#f0f',
green: '#008000',
lime: '#0f0',
maroon: '#800000',
navy: '#000080',
olive: '#808000',
orange:'#ffa500',
red: '#f00',
silver: '#c0c0c0',
teal: '#008080',
transparent:'rgba(0,0,0,0)',
white: '#fff',
yellow: '#ff0'
}
if(!!color[value]){
value = color[value]
}
if(value == "inherit"){
return getStyle(el.parentNode,style);
}
if(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/.test(value)){
return rgb2hex(value)
}else if(/^#/.test(value)){
value = value.replace('#', '');
return "#" + (value.length == 3 ? value.replace(/^(\w)(\w)(\w)$/, '$1$1$2$2$3$3') : value);
}
return value;
}
}
return value;//如 0px
}
var css = function(){
var a = arguments;
if(a.length == 1){
return getStyle(this,a[0])
}
}
var _ = function(el){
var el = isElement(el)? el :document.getElementById(el);
var gene = !el.constructor ? el : el.constructor.prototype;
gene.css = css;
gene.width = function(){
return getStyle(this,"width");
};
gene.height = function(){
return getStyle(this,"height");
};
return el
}
if(!window._){ //为了避免与JQuery的$发生冲突，我用_作为类库唯一的全局变量
window['_'] =_;
}
_.q = isQuirk;
})()

用法如下：

复制代码 代码如下:

window.onload = function(){
alert(_("ccc").css("background-color"))
alert(_("aaa").css("width"))
alert(_(document.body).width())
};

我们可以用这个东西研究一下document.body与document.documentElement。

复制代码 代码如下:

function text(){
var body = document.body,html = document.documentElement;
_("w1").innerHTML = _(body).width();
_("w2").innerHTML = _(html).width();
_("h1").innerHTML = _(body).height();
_("h2").innerHTML = _(html).height();
_("ml1").innerHTML = _(body).css("margin-left");
_("ml2").innerHTML = _(html).css("margin-left");
_("mr1").innerHTML = _(body).css("margin-right");
_("mr2").innerHTML = _(html).css("margin-right");
_("mt1").innerHTML = _(body).css("margin-top");
_("mt2").innerHTML = _(html).css("margin-top");
_("mb1").innerHTML = _(body).css("margin-bottom");
_("mb2").innerHTML = _(html).css("margin-bottom");
_("pl1").innerHTML = _(body).css("padding-left");
_("pl2").innerHTML = _(html).css("padding-left");
_("pr1").innerHTML = _(body).css("padding-right");
_("pr2").innerHTML = _(html).css("padding-right");
_("bl1").innerHTML = _(body).css("border-left-width");
_("bl2").innerHTML = _(html).css("border-left-width");
_("br1").innerHTML = _(body).css("border-right-width");
_("br2").innerHTML = _(html).css("border-right-width");
_("qqq").innerHTML = !_.q ? "标准模式" : "怪癖模式";
_("t1").innerHTML = _(body).css("top");
_("t2").innerHTML = _(html).css("top");
_("l1").innerHTML = _(body).css("left");
_("l2").innerHTML = _(html).css("left");
_("ot1").innerHTML = body.offsetTop;
_("ot2").innerHTML = html.offsetTop;
_("ol1").innerHTML = body.offsetLeft;
_("ol2").innerHTML = html.offsetLeft;
_("ct1").innerHTML = body.clientTop;
_("ct2").innerHTML = html.clientTop;
_("cl1").innerHTML = body.clientLeft;
_("cl2").innerHTML = html.clientLeft;
_("cw1").innerHTML = body.clientWidth;
_("cw2").innerHTML = html.clientWidth;
_("ow1").innerHTML = body.offsetWidth;
_("ow2").innerHTML = html.offsetWidth;
_("sw1").innerHTML = body.scrollWidth;
_("sw2").innerHTML = html.scrollWidth;
}

<meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=8"> <style type="text/css"> html, body{ border: 0; } </style> <script type="text/javascript"> (function(){ var isQuirk = (document.documentMode) ? (document.documentMode==5) ? true : false : ((document.compatMode=="CSS1Compat") ? false : true); var isElement = function(el) { return !!(el && el.nodeType == 1); } var propCache = []; var propFloat = !+"\v1" ? 'styleFloat' : 'cssFloat'; var camelize = function(attr){ return attr.replace(/\-(\w)/g, function(all, letter){ return letter.toUpperCase(); }); } var memorize = function(prop) { //意思为：check out form cache return propCache[prop] || (propCache[prop] = prop == 'float' ? propFloat : camelize(prop)); } var getIEOpacity = function(el){ var filter; if(!!window.XDomainRequest){ filter = el.style.filter.match(/progid:DXImageTransform.Microsoft.Alpha\(.?opacity=(.*).?\)/i); }else{ filter = el.style.filter.match(/alpha\(opacity=(.*)\)/i); } if(filter){ var value = parseFloat(filter[1]); if (!isNaN(value)) { return value ? value / 100 : 0; } } return 1; } var convertPixelValue = function(el, value){ var style = el.style,left = style.left,rsLeft = el.runtimeStyle.left; el.runtimeStyle.left = el.currentStyle.left; style.left = value || 0; var px = style.pixelLeft; style.left = left;//还原数据 el.runtimeStyle.left = rsLeft;//还原数据 return px + "px" } var rgb2hex = function(rgb) { rgb = rgb.match(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/); return "#"+tohex(rgb[1])+tohex(rgb[2])+tohex(rgb[3]) } var tohex = function(x) { var hexDigits = ['0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F']; return isNaN(x) ? '00' : hexDigits[(x - x % 16) / 16] + hexDigits[x % 16]; } var getStyle = function (el, style){ var value; if(!+"\v1"){ //特殊处理IE的opacity if(style == "opacity"){ return getIEOpacity(el) } value = el.currentStyle[memorize(style)]; //特殊处理IE的height与width if (/^(height|width)$/.test(style)){ var values = (style == 'width') ? ['left', 'right'] : ['top', 'bottom'], size = 0; if(isQuirk){ return el[camelize("offset-"+style)] + "px" }else{ var client = parseFloat(el[camelize("client-"+style)]), paddingA = parseFloat(getStyle(el, "padding-"+ values[0])), paddingB = parseFloat(getStyle(el, "padding-"+ values[1])); return (client - paddingA - paddingB)+"px"; } } }else{ if(style == "float"){ style = propFloat; } value = document.defaultView.getComputedStyle(el, null).getPropertyValue(style) } //下面部分全部用来转换上面得出的非精确值 if(!/^\d+px$/.test(value)){ //转换可度量的值 if(/(em|pt|mm|cm|pc|in|ex|rem|vw|vh|vm|ch|gr)$/.test(value)){ return convertPixelValue(el,value); } //转换百分比，不包括字体 if(/%$/.test(value) && style != "font-size"){ return parseFloat(getStyle(el.parentNode,"width")) * parseFloat(value) /100 + "px" } //转换border的thin medium thick if(/^(border).+(width)$/.test(style)){ var s = style.replace("width","style"), b = { thin:["1px","2px"], medium:["3px","4px"], thick:["5px","6px"] }; if(value == "medium" && getStyle(el,s) == "none"){ return "0px"; } return !!window.XDomainRequest ? b[value][0] : b[value][1]; } //转换margin的auto if(/^(margin).+/.test(style) && value == "auto"){ var father = el.parentNode; if(/MSIE 6/.test(navigator.userAgent) && getStyle(father,"text-align") == "center"){ var fatherWidth = parseFloat(getStyle(father,"width")), _temp = getStyle(father,"position"); father.runtimeStyle.postion = "relative"; var offsetWidth = el.offsetWidth; father.runtimeStyle.postion = _temp; return (fatherWidth - offsetWidth)/2 + "px"; } return "0px"; } //转换top|left|right|bottom的auto if(/(top|left|right|bottom)/.test(style) && value == "auto"){ return el.getBoundingClientRect()[style]; } //转换颜色 if(style.search(/background|color/) != -1) { var color = { aqua: '#0ff', black: '#000', blue: '#00f', gray: '#808080', purple: '#800080', fuchsia: '#f0f', green: '#008000', lime: '#0f0', maroon: '#800000', navy: '#000080', olive: '#808000', orange:'#ffa500', red: '#f00', silver: '#c0c0c0', teal: '#008080', transparent:'rgba(0,0,0,0)', white: '#fff', yellow: '#ff0' } if(!!color[value]){ value = color[value] } if(value == "inherit"){ return getStyle(el.parentNode,style); } if(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/.test(value)){ return rgb2hex(value) }else if(/^#/.test(value)){ value = value.replace('#', ''); return "#" + (value.length == 3 ? value.replace(/^(\w)(\w)(\w)$/, '$1$1$2$2$3$3') : value); } return value; } } return value;//如 0px } var css = function(){ var a = arguments; if(a.length == 1){ return getStyle(this,a[0]) } } var _ = function(el){ var el = isElement(el)? el :document.getElementById(el); var gene = !el.constructor ? el : el.constructor.prototype; gene.css = css; gene.width = function(){ //重写width return getStyle(this,"width"); }; gene.height = function(){ //重写height return getStyle(this,"height"); }; return el } if(!window._){ //为了避免与JQuery的$发生冲突，我用_作为类库唯一的全局变量 window['_'] =_; } _.q = isQuirk; })() function text(){ var body = document.body,html = document.documentElement; _("w1").innerHTML = _(body).width(); _("w2").innerHTML = _(html).width(); _("h1").innerHTML = _(body).height(); _("h2").innerHTML = _(html).height(); _("ml1").innerHTML = _(body).css("margin-left"); _("ml2").innerHTML = _(html).css("margin-left"); _("mr1").innerHTML = _(body).css("margin-right"); _("mr2").innerHTML = _(html).css("margin-right"); _("mt1").innerHTML = _(body).css("margin-top"); _("mt2").innerHTML = _(html).css("margin-top"); _("mb1").innerHTML = _(body).css("margin-bottom"); _("mb2").innerHTML = _(html).css("margin-bottom"); _("pl1").innerHTML = _(body).css("padding-left"); _("pl2").innerHTML = _(html).css("padding-left"); _("pr1").innerHTML = _(body).css("padding-right"); _("pr2").innerHTML = _(html).css("padding-right"); _("bl1").innerHTML = _(body).css("border-left-width"); _("bl2").innerHTML = _(html).css("border-left-width"); _("br1").innerHTML = _(body).css("border-right-width"); _("br2").innerHTML = _(html).css("border-right-width"); _("qqq").innerHTML = !_.q ? "标准模式" : "怪癖模式"; _("t1").innerHTML = _(body).css("top"); _("t2").innerHTML = _(html).css("top"); _("l1").innerHTML = _(body).css("left"); _("l2").innerHTML = _(html).css("left"); _("ot1").innerHTML = body.offsetTop; _("ot2").innerHTML = html.offsetTop; _("ol1").innerHTML = body.offsetLeft; _("ol2").innerHTML = html.offsetLeft; _("ct1").innerHTML = body.clientTop; _("ct2").innerHTML = html.clientTop; _("cl1").innerHTML = body.clientLeft; _("cl2").innerHTML = html.clientLeft; _("cw1").innerHTML = body.clientWidth; _("cw2").innerHTML = html.clientWidth; _("ow1").innerHTML = body.offsetWidth; _("ow2").innerHTML = html.offsetWidth; _("sw1").innerHTML = body.scrollWidth; _("sw2").innerHTML = html.scrollWidth; } </script> <title>精确取值</title> <table border="1"> <thead> <th>测试属性</th> <th>document.body</th> <th>document.documentElement</th> </thead> <tbody> <tr> <th>width</th> <td><span id="w1"></span></td> <td><span id="w2"></span></td> </tr> <tr> <th>height</th> <td><span id="h1"></span></td> <td><span id="h2"></span></td> </tr> <tr> <th>margin-left</th> <td><span id="ml1"></span></td> <td><span id="ml2"></span></td> </tr> <tr> <th>margin-right</th> <td><span id="mr1"></span></td> <td><span id="mr2"></span></td> </tr> <tr> <th>margin-top</th> <td><span id="mt1"></span></td> <td><span id="mt2"></span></td> </tr> <tr> <th>margin-bottom</th> <td><span id="mb1"></span></td> <td><span id="mb2"></span></td> </tr> <tr> <th>padding-left</th> <td><span id="pl1"></span></td> <td><span id="pl2"></span></td> </tr> <tr> <th>padding-right</th> <td><span id="pr1"></span></td> <td><span id="pr2"></span></td> </tr> <tr> <th>border-left-width</th> <td><span id="bl1"></span></td> <td><span id="bl2"></span></td> </tr> <tr> <th>border-right-width</th> <td><span id="br1"></span></td> <td><span id="br2"></span></td> </tr> <tr> <th>渲染模式</th> <td colspan="2"><span id="qqq"></span></td> </tr> <tr> <th>top</th> <td><span id="t1"></span></td> <td><span id="t2"></span></td> </tr> <tr> <th>left</th> <td><span id="l1"></span></td> <td><span id="l2"></span></td> </tr> <tr> <th>offsetTop</th> <td><span id="ot1"></span></td> <td><span id="ot2"></span></td> </tr> <tr> <th>offsetLeft</th> <td><span id="ol1"></span></td> <td><span id="ol2"></span></td> </tr> <tr> <th>clientTop</th> <td><span id="ct1"></span></td> <td><span id="ct2"></span></td> </tr> <tr> <th>clientLeft</th> <td><span id="cl1"></span></td> <td><span id="cl2"></span></td> </tr> <tr> <th>offsetWidth</th> <td><span id="ow1"></span></td> <td><span id="ow2"></span></td> </tr> <tr> <th>clientWidth</th> <td><span id="cw1"></span></td> <td><span id="cw2"></span></td> </tr> <tr> <th>scrollWidth</th> <td><span id="sw1"></span></td> <td><span id="sw2"></span></td> </tr> </tbody> </table> <p><button type="button" onclick="text()">运行代码</button></p> <br>　 <br><br> <br><br> <br><br> <br><br> <br><br> <br>
[Ctrl+A 全选 注:如需引入外部Js需刷新才能执行]

在标准模式下，火狐等浏览器中我们看到offsetWidth等值最大为1007，因为火狐的offsetWidth不大于clientWidth，而clientWidth是不包含滚动条（滚动条的宽都固定为17px）。在IE中，offsetWidth是比clientWidth多了两个border，由此发现问题，1024-1003-17=4，4应该是两个auto生成，而这个auto应该为border的值，这两个border在IE中是固定死，不能通过以下手段修改。

复制代码 代码如下:

换言之，在标准模式下，IE的html是存在不可修改的宽为2px的border。也换言之，我的程序是有个BUG，没有正确显示出html的border为2px，囧。
再看怪癖模式，
火狐等没有所谓的怪癖模式，直接看IE的。发现那神秘的2px又出现，这时出现在document.body的clientTop，clientLeft中。那么怪癖模式下的document.body的clientTop，clientLeft又相当于CSS的什么概念呢？我们来看微软给出的一幅老图，那时IE5独步天下，没有所谓标准模式与怪癖模式之分，因此这幅图的东西都是按怪癖模式表示的。

不难看出，clientLeft相当于borderLeft，clientTop相当于borderTop。至于上面的border-left-width与border-right-width，就不要看了，是错误，因为我当初就没有考虑这两个元素在标准模式与怪癖模式下的问题。既然document.body的边框区就达1024px了，那么html元素的脸往哪里搁呢？！对不起，在微软早期的设想，body元素才是代表文档（一个强有力的证据是，在怪癖模式下，网页的滚动条是位于body元素中）。模准模式连同火狐那帮失败者宣扬的各种没有市场份额的“标准”，都是在微软极不情愿下支持的。你看，documentElement这样累赘傻气的名字像是微软起的吗？！如果是微软，它应该就叫html，和document.boy那样简洁。搞到在标准模式下，我们取scrollLeft，要用document.documentElement.scrollLeft，因为这时body不存在滚动条；在怪癖模式下，要用document.body，虽然微软以打补丁的方法添加上document.documentElement（真拗口，难怪网景会失败），但滚动条的位置不是说变就变。
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