这一节重点讲jQuery对样式的处理，虽然IE同时拥有style,currentStyle与runtimeStyle，但没有一个能获取used value，这是原罪。直接导致的结果是处理样式，就是处理IE的非精确值问题，有时能否获得值也是个大问题。jQuery与其他类库一样，在这方面下了很大工夫，最终在这方面打败其他类库。
001. //这里的代码写得很垃圾啊，不过这样写肯定有它的道理，既然版本号已经发展1.32，那当然是那么兼容以前的代码设计的 002. className: { 003. //顺便一提className与arguments一样是个类数组 004. add: function( elem, classNames ) { 005. jQuery.each((classNames || "").split(/\s+/), function(i, className){ 006. if ( elem.nodeType == 1 && !jQuery.className.has( elem.className, className ) ) 007. elem.className += (elem.className ? " " : "") + className; 008. }); 009. }, 010. // internal only, use removeClass("class") 011. remove: function( elem, classNames ) { 012. //觉得什么都用自定义函数解决效率太低了，更何况jQuery.grep的逻辑如此复杂 013. if (elem.nodeType == 1) 014. elem.className = classNames !== undefined ? 015. jQuery.grep(elem.className.split(/\s+/), function(className){ 016. return !jQuery.className.has( classNames, className ); 017. }).join(" ") : 018. ""; 019. }, 020. // internal only, use hasClass("class") 021. has: function( elem, className ) { 022. return elem && jQuery.inArray( className, (elem.className || elem).toString().split(/\s+/) ) > -1; 023. } 024. }, 025. //这是一个非常重要的内部函数，用于精确获取样式值 026. // A method for quickly swapping in/out CSS properties to get correct calculations 027. swap: function( elem, options, callback ) { 028. var old = {};//备份用 029. // Remember the old values, and insert the new ones 030. for ( var name in options ) { 031. old[ name ] = elem.style[ name ]; 032. elem.style[ name ] = options[ name ]; 033. } 034. //交换之后调用测试函数 035. callback.call( elem ); 036. //测试完后还原 037. // Revert the old values 038. for ( var name in options ) 039. elem.style[ name ] = old[ name ]; 040. }, 041. //jQuery对象也有一个与它同名的方法，但这不是简单的代理 042. //不过实际路线图为原型的css→原型的attr→静态的attr→静态的css 043. //最后是curCSS，这才是真身 044. css: function( elem, name, force, extra ) { 045. //处理宽与高，因为IE不能正确返回以px为单位的精确值 046. if ( name == "width" || name == "height" ) { 047. //props用于swap，一个聪明的手段，值得学习 048. var val, props = { position: "absolute", visibility: "hidden", display:"block" }, which = name == "width" ? [ "Left", "Right" ] : [ "Top", "Bottom" ]; 049. function getWH() { 050. //Ext与Prototypet等类库也是这样实现 051. //在标准模式中，offsetWidth是包含padding，borderWidth与width 052. //在怪癖模式下，offsetWidth等于width，而width是包含padding与borderWidth 053. //offsetHeight同理 054. val = name == "width" ? elem.offsetWidth : elem.offsetHeight; 055. if ( extra === "border" ) 056. return; 057. jQuery.each( which, function() { 058. if ( !extra ) 059. //求出paddingLeft与paddingRight之和，或paddingTop与paddingBottom之和， 060. //然后作为减数，去减offsetWidth或offsetHeight 061. val -= parseFloat(jQuery.curCSS( elem, "padding" + this, true)) || 0; 062. if ( extra === "margin" ) 063. val += parseFloat(jQuery.curCSS( elem, "margin" + this, true)) || 0; 064. else065. val -= parseFloat(jQuery.curCSS( elem, "border" + this + "Width", true)) || 0; 066. }); 067. } 068. if ( elem.offsetWidth !== 0 ) 069. getWH(); 070. else071. //如果display:none就求不出offsetWidht与offsetHeight，swap一下 072. jQuery.swap( elem, props, getWH ); 073. return Math.max(0, Math.round(val)); 074. } 075. //再调用jQuery.curCSS进行深加工 076. return jQuery.curCSS( elem, name, force ); 077.}, 078.curCSS: function( elem, name, force ) { 079. var ret, style = elem.style; 080. // We need to handle opacity special in IE 081. if ( name == "opacity" && !jQuery.support.opacity ) { 082. ret = jQuery.attr( style, "opacity" ); 083. return ret == "" ? 084. "1" : 085. ret; 086. } 087. // Make sure we're using the right name for getting the float value 088. if ( name.match( /float/i ) ) 089. name = styleFloat; 090. if ( !force && style && style[ name ] ) 091. ret = style[ name ];//缓存结果 092. else if ( defaultView.getComputedStyle ) { 093. //标准浏览器 094. // Only "float" is needed here 095. if ( name.match( /float/i ) ) 096. name = "float";//把cssFloat转换为float 097. //把驼峰风格转换为连字符风格 098. name = name.replace( /([A-Z])/g, "-$1" ).toLowerCase(); 099. var computedStyle = defaultView.getComputedStyle( elem, null ); 100. if ( computedStyle ) 101. ret = computedStyle.getPropertyValue( name ); 102. // We should always get a number back from opacity 103. if ( name == "opacity" && ret == "" ) 104. ret = "1";//把opacity设置成1 105. } else if ( elem.currentStyle ) { 106. //IE浏览器部分 107. var camelCase = name.replace(/\-(\w)/g, function(all, letter){ 108. return letter.toUpperCase(); 109. }); 110. //把连字符风格转换为驼峰风格 111. ret = elem.currentStyle[ name ] || elem.currentStyle[ camelCase ]; 112. // From the awesome hack by Dean Edwards 113. // http://erik.eae.net/archives/2007/07/27/18.54.15/#comment-102291 114. // If we're not dealing with a regular pixel number 115. // but a number that has a weird ending, we need to convert it to pixels 116. //将不是以px为单位的计算值全部转换为以px为单位，用到 Dean Edwards（Base2类库的作者）的hack 117. //网上有文章讲解这hach，这里不重复 118. if ( !/^\d+(px)?$/i.test( ret ) && /^\d/.test( ret ) ) { 119. // Remember the original values 120. var left = style.left, rsLeft = elem.runtimeStyle.left; 121. // Put in the new values to get a computed value out 122. elem.runtimeStyle.left = elem.currentStyle.left; 123. style.left = ret || 0; 124. ret = style.pixelLeft + "px"; 125. // Revert the changed values 126. style.left = left; 127. elem.runtimeStyle.left = rsLeft; 128. } 129. } 130. return ret; 131.}, 132.attr: function( elem, name, value ) { 133. // 文本，注释节点不处理 134. if (!elem || elem.nodeType == 3 || elem.nodeType == 8) 135. return undefined; 136. //不处理xml文档的 137. var notxml = !jQuery.isXMLDoc( elem ), 138. //是读方法还是写方法 139. set = value !== undefined; 140. // Try to normalize/fix the name 141. //兼容处理， 142. //jQuery.props = { 143. //"for": "htmlFor", 144. //"class": "className", 145. //"float": styleFloat, 146. //cssFloat: styleFloat, 147. //styleFloat: styleFloat, 148. //readonly: "readOnly", 149. //maxlength: "maxLength", 150. //cellspacing: "cellSpacing", 151. //rowspan: "rowSpan", 152. //tabindex: "tabIndex" 153. //}; 154. name = notxml && jQuery.props[ name ] || name; 155. // Only do all the following if this is a node (faster for style) 156. // IE elem.getAttribute passes even for style 157. if ( elem.tagName ) { 158. // These attributes require special treatment 159. var special = /href|src|style/.test( name ); 160. // Safari mis-reports the default selected property of a hidden option 161. // Accessing the parent's selectedIndex property fixes it 162. //修正无法取得selected正确值的bug 163. if ( name == "selected" && elem.parentNode ) 164. elem.parentNode.selectedIndex; 165. // If applicable, access the attribute via the DOM 0 way 166. if ( name in elem && notxml && !special ) { 167. if ( set ){ 168. //不允许改写type的值 169. // We can't allow the type property to be changed (since it causes problems in IE) 170. if ( name == "type" && jQuery.nodeName( elem, "input" ) && elem.parentNode ) 171. throw "type property can't be changed"; 172. elem[ name ] = value; 173. } 174. // browsers index elements by id/name on forms, give priority to attributes. 175. if( jQuery.nodeName( elem, "form" ) && elem.getAttributeNode(name) ) 176. //getAttributeNode() 方法的作用是：通过指定的名称获取当前元素中的属性节点。 177. return elem.getAttributeNode( name ).nodeValue; 178. // elem.tabIndex doesn't always return the correct value when it hasn't been explicitly set 180. //IE只能tabIndex 181. //标准浏览器用tabindex 182. if ( name == "tabIndex" ) { 183. var attributeNode = elem.getAttributeNode( "tabIndex" ); 184. return attributeNode && attributeNode.specified 185. ? attributeNode.value 186. : elem.nodeName.match(/(button|input|object|select|textarea)/i) 187. ? 0 188. : elem.nodeName.match(/^(a|area)$/i) && elem.href 189. ? 0 190. : undefined; 191. } 192. return elem[ name ]; 193. } 194. if ( !jQuery.support.style && notxml && name == "style" ) 195. return jQuery.attr( elem.style, "cssText", value ); 196. if ( set ) 197. // convert the value to a string (all browsers do this but IE) see #1070 198. elem.setAttribute( name, "" + value ); 199. //IE的getAttribute支持第二个参数，可以为 0,1,2 200. //0 是默认；1 区分属性的大小写；2取出源代码中的原字符串值。 201. //IE 在取 href 的时候默认拿出来的是绝对路径，加参数2得到我们所需要的相对路径。 202. var attr = !jQuery.support.hrefNormalized && notxml && special 203. // Some attributes require a special call on IE 204. ? elem.getAttribute( name, 2 ) 205. : elem.getAttribute( name ); 206. // Non-existent attributes return null, we normalize to undefined 207. return attr === null ? undefined : attr; 208. } 209. // elem is actually elem.style ... set the style 210. // IE uses filters for opacity 211. if ( !jQuery.support.opacity && name == "opacity" ) { 212. if ( set ) { 213. // IE has trouble with opacity if it does not have layout 214. // Force it by setting the zoom level 215. //IE7中滤镜（filter）必须获得hasLayout才能生效，我们用zoom这个IE私有属性让其获得hasLayout 216. elem.zoom = 1; 217. // Set the alpha filter to set the opacity 218. elem.filter = (elem.filter || "").replace( /alpha\([^)]*\)/, "" ) + 219. (parseInt( value ) + '' == "NaN" ? "" : "alpha(opacity=" + value * 100 + ")"); 220. } 221. return elem.filter && elem.filter.indexOf("opacity=") >= 0 ? 222. (parseFloat( elem.filter.match(/opacity=([^)]*)/)[1] ) / 100) + '': 223. ""; 224. } 225. //获得其他属性，直接用DOM 0方法读写 226. name = name.replace(/-([a-z])/ig, function(all, letter){ 227. return letter.toUpperCase(); 228. }); 229. if ( set ) 230. elem[ name ] = value; 231. return elem[ name ]; 232.},其实在curCss与attr方法中还夹着一个clean方法，总觉得clean职责太多，里面分支繁缛，看得我头晕眼花……太凌乱，这方法应该分割成几个方法条理更清晰，效率更高。
001.//把字符串转换为DOM元素的纯数组 002.//这里的elems为字符串数组，将用文档碎片做转换 003.clean: function( elems, context, fragment ) { 004. context = context || document; 005. // !context.createElement fails in IE with an error but returns typeof 'object' 006. if ( typeof context.createElement === "undefined" ) 007. context = context.ownerDocument || context[0] && context[0].ownerDocument || document; 008. // If a single string is passed in and it's a single tag 009. // just do a createElement and skip the rest 010. if ( !fragment && elems.length === 1 && typeof elems[0] === "string" ) { 011. var match = /^<(\w+)\s*\/?>$/.exec(elems[0]); 012. if ( match ) 013. return [ context.createElement( match[1] ) ]; 014. } 015. //div是用于把字符串转换为DOM的 016. var ret = [], scripts = [], div = context.createElement("div"); 017. jQuery.each(elems, function(i, elem){ 018. if ( typeof elem === "number" ) 019. elem += '';//转换为字符串 020. if ( !elem ) 021. return; 022. // Convert html string into DOM nodes 023. if ( typeof elem === "string" ) { 024. // Fix "XHTML"-style tags in all browsers 025. //生成闭合的标签对，亦即把在XHTML中不合法的写法强制转换过来 026. elem = elem.replace(/(<(\w+)[^>]*?)\/>/g, function(all, front, tag){ 027. //但对于abbr|br|col|img|input|link|meta|param|hr|area|embed等元素不修改 028. return tag.match(/^(abbr|br|col|img|input|link|meta|param|hr|area|embed)$/i) ? 029. all : 030. front + "></" + tag + ">"; 031. }); 032. // Trim whitespace, otherwise indexOf won't work as expected 033. //将“ <div> ”去掉两边的空白“<div>”，用于下面的indexOf 034. var tags = elem.replace(/^\s+/, "").substring(0, 10).toLowerCase(); 035. var wrap = 036. // option or optgroup 037. //option与optgroup的直接父元素一定是select 038. !tags.indexOf("<opt") && 039. [ 1, "<select multiple='multiple'>", "</select>" ] || 040. //legend的直接父元素一定是fieldset 041. !tags.indexOf("<leg") && 042. [ 1, "<fieldset>", "</fieldset>" ] || 043. //thead,tbody,tfoot,colgroup,caption的直接父元素一定是table 044. tags.match(/^<(thead|tbody|tfoot|colg|cap)/) && 045. [ 1, "<table>", "</table>" ] || 046. //tr的直接父元素一定是tbody， 047. !tags.indexOf("<tr") && 048. [ 2, "<table><tbody>", "</tbody></table>" ] || 049. //<thead> matched above 050. //td与th的直接父元素一定是tr 051. (!tags.indexOf("<td") || !tags.indexOf("<th")) && 052. [ 3, "<table><tbody><tr>", "</tr></tbody></table>" ] || 053. //col一定是colgroup 054. !tags.indexOf("<col") && 055. [ 2, "<table><tbody></tbody><colgroup>", "</colgroup></table>" ] || 056. // IE can't serialize <link> and <script> tags normally 057. !jQuery.support.htmlSerialize && 058. [ 1, "div<div>", "</div>" ] || 059. [ 0, "", "" ]; 060. // Go to html and back, then peel off extra wrappers 061. div.innerHTML = wrap[1] + elem + wrap[2]; 062. // Move to the right depth 063. while ( wrap[0]-- ) 064. div = div.lastChild; 065. //IE会自动添加tbody，要特殊处理 066. // Remove IE's autoinserted <tbody> from table fragments 067. if ( !jQuery.support.tbody ) { 068. // String was a <table>, *may* have spurious <tbody> 069. var hasBody = /<tbody/i.test(elem), 070. tbody = !tags.indexOf("<table") && !hasBody ? 071. div.firstChild && div.firstChild.childNodes : 072. // String was a bare <thead> or <tfoot> 073. wrap[1] == "<table>" && !hasBody ? 074. div.childNodes : 075. []; 076. for ( var j = tbody.length - 1; j >= 0 ; --j ) 077. if ( jQuery.nodeName( tbody[ j ], "tbody" ) && !tbody[ j ].childNodes.length ) 078. tbody[ j ].parentNode.removeChild( tbody[ j ] ); 079. } 080. // IE completely kills leading whitespace when innerHTML is used 081. if ( !jQuery.support.leadingWhitespace && /^\s/.test( elem ) ) 082. div.insertBefore( context.createTextNode( elem.match(/^\s*/)[0] ), div.firstChild ); 083. //div中的所有节点都转换为数组 084. elem = jQuery.makeArray( div.childNodes ); 085. } 086. if ( elem.nodeType ) 087. //过滤非元素节点的节点 088. ret.push( elem ); 089. else090. //把符合要求的节点加入ret中 091. ret = jQuery.merge( ret, elem ); 092. }); 093. if ( fragment ) { 094. for ( var i = 0; ret[i]; i++ ) { 095. //处理script元素 096. if ( jQuery.nodeName( ret[i], "script" ) && (!ret[i].type || ret[i].type.toLowerCase() === "text/javascript") ) { 097. scripts.push( ret[i].parentNode ? ret[i].parentNode.removeChild( ret[i] ) : ret[i] ); 098. } else { 099. if ( ret[i].nodeType === 1 ) 100. ret.splice.apply( ret, [i + 1, 0].concat(jQuery.makeArray(ret[i].getElementsByTagName("script"))) ); 101. fragment.appendChild( ret[i] ); 102. } 103. } 104. return scripts; 105. } 106. return ret; 107.},
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