0770: // A method for quickly swapping in/out CSS properties to get correct calculations
0771: swap: function( elem, options, callback ) {
0772:   var old = {};
0773:   // Remember the old values, and insert the new ones
0774:   for ( var name in options ) {
0775:     old[ name ] = elem.style[ name ];
0776:     elem.style[ name ] = options[ name ];
0777:   }
0778:
0779:   callback.call( elem );
0780:
0781:   // Revert the old values
0782:   for ( var name in options )
0783:     elem.style[ name ] = old[ name ];
0784: },
0785:

0786: css: function( elem, name, force ) {
0787:   if ( name == "width" || name == "height" ) {
0788:     var val, props = { position: "absolute", visibility: "hidden", display:"block" }, which = name == "width" ? [ "Left", "Right" ] : [ "Top", "Bottom" ];
0789:   
0790:     function getWH() {
0791:       val = name == "width" ? elem.offsetWidth : elem.offsetHeight;
0792:       var padding = 0, border = 0;
0793:       jQuery.each( which, function() {
0794:         padding += parseFloat(jQuery.curCSS( elem, "padding" + this, true)) || 0;
0795:         border += parseFloat(jQuery.curCSS( elem, "border" + this + "Width", true)) || 0;
0796:       });
0797:       val -= Math.round(padding + border);
0798:     }
0799:   
0800:     if ( jQuery(elem).is(":visible") )
0801:       getWH();
0802:     else
0803:       jQuery.swap( elem, props, getWH );
0804:     
0805:     return Math.max(0, val);
0806:   }
0807:   
0808:   return jQuery.curCSS( elem, name, force );
0809: },
0810:

0811: curCSS: function( elem, name, force ) {
0812:   var ret;
0813:
0814:   // A helper method for determining if an element's values are broken
0815:   function color( elem ) {
0816:     if ( !jQuery.browser.safari )
0817:       return false;
0818:
0819:     var ret = document.defaultView.getComputedStyle( elem, null );
0820:     return !ret || ret.getPropertyValue("color") == "";
0821:   }
0822:
0823:   // We need to handle opacity special in IE
0824:   if ( name == "opacity" && jQuery.browser.msie ) {
0825:     ret = jQuery.attr( elem.style, "opacity" );
0826:
0827:     return ret == "" ?
0828:       "1" :
0829:       ret;
0830:   }
0831:   // Opera sometimes will give the wrong display answer, this fixes it, see #2037
0832:   if ( jQuery.browser.opera && name == "display" ) {
0833:     var save = elem.style.display;
0834:     elem.style.display = "block";
0835:     elem.style.display = save;
0836:   }
0837:   
0838:   // Make sure we're using the right name for getting the float value
0839:   if ( name.match( /float/i ) )
0840:     name = styleFloat;
0841:

0842:   if ( !force && elem.style && elem.style[ name ] )
0843:     ret = elem.style[ name ];
0844:

0845:   else if ( document.defaultView && document.defaultView.getComputedStyle ) {
0846:
0847:     // Only "float" is needed here
0848:     if ( name.match( /float/i ) )
0849:       name = "float";
0850:
0851:     name = name.replace( /([A-Z])/g, "-$1" ).toLowerCase();
0852:
0853:     var getComputedStyle = document.defaultView.getComputedStyle( elem, null );
0854:
0855:     if ( getComputedStyle && !color( elem ) )
0856:       ret = getComputedStyle.getPropertyValue( name );
0857:
0858:     // If the element isn't reporting its values properly in Safari
0859:     // then some display: none elements are involved
0860:     else {
0861:       var swap = [], stack = [];
0862:
0863:       // Locate all of the parent display: none elements
0864:       for ( var a = elem; a && color(a); a = a.parentNode )
0865:         stack.unshift(a);
0866:
0867:       // Go through and make them visible, but in reverse
0868:       // (It would be better if we knew the exact display type that they had)
0869:       for ( var i = 0; i 0870:         if ( color( stack[ i ] ) ) {
0871:           swap[ i ] = stack[ i ].style.display;
0872:           stack[ i ].style.display = "block";
0873:         }
0874:
0875:       // Since we flip the display style, we have to handle that
0876:       // one special, otherwise get the value
0877:       ret = name == "display" && swap[ stack.length - 1 ] != null ?
0878:         "none" :
0879:         ( getComputedStyle && getComputedStyle.getPropertyValue( name ) ) || "";
0880:
0881:       // Finally, revert the display styles back
0882:       for ( var i = 0; i 0883:         if ( swap[ i ] != null )
0884:           stack[ i ].style.display = swap[ i ];
0885:     }
0886:
0887:     // We should always get a number back from opacity
0888:     if ( name == "opacity" && ret == "" )
0889:       ret = "1";
0890:

0891:   } else if ( elem.currentStyle ) {
0892:     var camelCase = name.replace(/\-(\w)/g, function(all, letter){
0893:       return letter.toUpperCase();
0894:     });
0895:
0896:     ret = elem.currentStyle[ name ] || elem.currentStyle[ camelCase ];
0897:

0898:     // From the awesome hack by Dean Edwards
0899:     // http://erik.eae.net/archives/2007/07/27/18.54.15/#comment-102291
0900:
0901:     // If we're not dealing with a regular pixel number
0902:     // but a number that has a weird ending, we need to convert it to pixels
0903:     if ( !/^\d+(px)?$/i.test( ret ) && /^\d/.test( ret ) ) {
0904:       // Remember the original values
0905:       var style = elem.style.left, runtimeStyle = elem.runtimeStyle.left;
0906:
0907:       // Put in the new values to get a computed value out
0908:       elem.runtimeStyle.left = elem.currentStyle.left;
0909:       elem.style.left = ret || 0;
0910:       ret = elem.style.pixelLeft + "px";
0911:
0912:       // Revert the changed values
0913:       elem.style.left = style;
0914:       elem.runtimeStyle.left = runtimeStyle;
0915:     }
0916:   }
0917:
0918:   return ret;
0919: },
0920: 

0921: clean: function( elems, context ) {
0922:   var ret = [];
0923:   context = context || document;
0924:   // !context.createElement fails in IE with an error but returns typeof 'object'
0925:   if (typeof context.createElement == 'undefined') 
0926:     context = context.ownerDocument || context[0] && context[0].ownerDocument || document;
0927:
0928:   jQuery.each(elems, function(i, elem){
0929:     if ( !elem )
0930:       return;
0931:
0932:     if ( elem.constructor == Number )
0933:       elem = elem.toString();
0934:     
0935:     // Convert html string into DOM nodes
0936:     if ( typeof elem == "string" ) {
0937:       // Fix "XHTML"-style tags in all browsers
0938:       elem = elem.replace(/(<(\w+)[^>]*?)\/>/g, function(all, front, tag){
0939:         return tag.match(/^(abbr|br|col|img|input|link|meta|param|hr|area|embed)$/i) ?
0940:           all :
0941:           front + "></" + tag + ">";
0942:       });
0943:
0944:       // Trim whitespace, otherwise indexOf won't work as expected
0945:       var tags = jQuery.trim( elem ).toLowerCase(), div = context.createElement("div");
0946:
0947:       var wrap =
0948:         // option or optgroup
0949:         !tags.indexOf("<opt") &&
0950:         [ 1, "<select multiple='multiple'>", "</select>" ] ||
0951:         
0952:         !tags.indexOf("<leg") &&
0953:         [ 1, "<fieldset>", "</fieldset>" ] ||
0954:         
0955:         tags.match(/^<(thead|tbody|tfoot|colg|cap)/) &&
0956:         [ 1, "<table>", "</table>" ] ||
0957:         
0958:         !tags.indexOf("<tr") &&
0959:         [ 2, "<table><tbody>", "</tbody></table>" ] ||
0960:         
0961:          // <thead> matched above
0962:         (!tags.indexOf("<td") || !tags.indexOf("<th")) &&
0963:         [ 3, "<table><tbody><tr>", "</tr></tbody></table>" ] ||
0964:         
0965:         !tags.indexOf("<col") &&
0966:         [ 2, "<table><tbody></tbody><colgroup>", "</colgroup></table>" ] ||
0967:
0968:         // IE can't serialize <link> and <script> tags normally
0969:         jQuery.browser.msie &&
0970:         [ 1, "div<div>", "</div>" ] ||
0971:         
0972:         [ 0, "", "" ];
0973:
0974:       // Go to html and back, then peel off extra wrappers
0975:       div.innerHTML = wrap[1] + elem + wrap[2];
0976:       
0977:       // Move to the right depth
0978:       while ( wrap[0]-- )
0979:         div = div.lastChild;
0980:       
0981:       // Remove IE's autoinserted <tbody> from table fragments
0982:       if ( jQuery.browser.msie ) {
0983:         
0984:         // String was a <table>, *may* have spurious 
0985:         var tbody = !tags.indexOf("<table") && tags.indexOf("<tbody") < 0 ?
0986:           div.firstChild && div.firstChild.childNodes :
0987:           
0988:           // String was a bare <thead> or <tfoot>
0989:           wrap[1] == "<table>" && tags.indexOf("<tbody") < 0 ?
0990:             div.childNodes :
0991:             [];
0992:       
0993:         for ( var j = tbody.length - 1; j >= 0 ; --j )
0994:           if ( jQuery.nodeName( tbody[ j ], "tbody" ) && !tbody[ j ].childNodes.length )
0995:             tbody[ j ].parentNode.removeChild( tbody[ j ] );
0996:         
0997:         // IE completely kills leading whitespace when innerHTML is used  
0998:         if ( /^\s/.test( elem ) )  
0999:           div.insertBefore( context.createTextNode( elem.match(/^\s*/)[0] ), div.firstChild );
1000:       
1001:       }
1002:       
1003:       elem = jQuery.makeArray( div.childNodes );
1004:     }
1005:
1006:     if ( elem.length === 0 && (!jQuery.nodeName( elem, "form" ) && !jQuery.nodeName( elem, "select" )) )
1007:       return;
1008:
1009:     if ( elem[0] == undefined || jQuery.nodeName( elem, "form" ) || elem.options )
1010:       ret.push( elem );
1011:
1012:     else
1013:       ret = jQuery.merge( ret, elem );
1014:
1015:   });
1016:
1017:   return ret;
1018: },
1019: 


jQuery.cleanメソッドは、内部でHTMLを利用しやすいように加工するためのメソッドです。
925行目では、contextにdocument以外が渡された場合、Internet ExplorerではcreateElementが失敗するため、contextの値を再設定しています。そして、928行目以降で渡されたすべての要素に対して、以下の処理を適用していきます。


937～942行目：空要素タグを分割
944～979行目：特定のタグの場合に適切なタグで囲む
981～1004行目：Internet Exploerで自動的に挿入されるtbodyタグを取り除く、innerHTMLで先頭の空白文字列を保存
1006～1013行目：formまたはselectがリターン用配列への格納



attr()


1020: attr: function( elem, name, value ) {
1021:   // don't set attributes on text and comment nodes
1022:   if (!elem || elem.nodeType == 3 || elem.nodeType == 8)
1023:     return undefined;
1024:
1025:   var fix = jQuery.isXMLDoc( elem ) ?
1026:     {} :
1027:     jQuery.props;
1028:
1029:   // Safari mis-reports the default selected property of a hidden option
1030:   // Accessing the parent's selectedIndex property fixes it
1031:   if ( name == "selected" && jQuery.browser.safari )
1032:     elem.parentNode.selectedIndex;
1033:   
1034:   // Certain attributes only work when accessed via the old DOM 0 way
1035:   if ( fix[ name ] ) {
1036:     if ( value != undefined )
1037:       elem[ fix[ name ] ] = value;
1038:
1039:     return elem[ fix[ name ] ];
1040:
1041:   } else if ( jQuery.browser.msie && name == "style" )
1042:     return jQuery.attr( elem.style, "cssText", value );
1043:
1044:   else if ( value == undefined && jQuery.browser.msie && jQuery.nodeName( elem, "form" ) && (name == "action" || name == "method") )
1045:     return elem.getAttributeNode( name ).nodeValue;
1046:
1047:   // IE elem.getAttribute passes even for style
1048:   else if ( elem.tagName ) {
1049:
1050:     if ( value != undefined ) {
1051:       // We can't allow the type property to be changed (since it causes problems in IE)
1052:       if ( name == "type" && jQuery.nodeName( elem, "input" ) && elem.parentNode )
1053:         throw "type property can't be changed";
1054:
1055:       // convert the value to a string (all browsers do this but IE) see #1070
1056:       elem.setAttribute( name, "" + value );
1057:     }
1058:
1059:     if ( jQuery.browser.msie && /href|src/.test( name ) && !jQuery.isXMLDoc( elem ) ) 
1060:       return elem.getAttribute( name, 2 );
1061:
1062:     return elem.getAttribute( name );
1063:
1064:   // elem is actually elem.style ... set the style
1065:   } else {
1066:     // IE actually uses filters for opacity
1067:     if ( name == "opacity" && jQuery.browser.msie ) {
1068:       if ( value != undefined ) {
1069:         // IE has trouble with opacity if it does not have layout
1070:         // Force it by setting the zoom level
1071:         elem.zoom = 1; 
1072: 
1073:         // Set the alpha filter to set the opacity
1074:         elem.filter = (elem.filter || "").replace( /alpha\([^)]*\)/, "" ) +
1075:           (parseFloat( value ).toString() == "NaN" ? "" : "alpha(opacity=" + value * 100 + ")");
1076:       }
1077: 
1078:       return elem.filter && elem.filter.indexOf("opacity=") >= 0 ?
1079:         (parseFloat( elem.filter.match(/opacity=([^)]*)/)[1] ) / 100).toString() :
1080:         "";
1081:     }
1082:
1083:     name = name.replace(/-([a-z])/ig, function(all, letter){
1084:       return letter.toUpperCase();
1085:     });
1086:
1087:     if ( value != undefined )
1088:       elem[ name ] = value;
1089:
1090:     return elem[ name ];
1091:   }
1092: },
1093: 


jQuery.attrメソッドは、属性値を扱うためのメソッドです。
1021～1023行目は、nodeTypeがテキストまたはコメントの場合は属性値は存在しないためundefinedを返します。
1029～1032行目は、Safariでselected値を取得しようとした時に発生する不具合を回避するため、親要素のselectedIndex値にアクセスしています。
1034～1040行目は、jQuery.propsで定義されている属性(1214行目)についてはDOM0に従ってアクセスします。
1041～1042行目は、IEからstyle属性にアクセスしようとしている場合は、jQuery.attr( elem.style, "cssText", value )として自分自身を呼び出します。
1044～1045行目は、IEからformのactionまたはmethodを取得しようとしている場合の処理です。
1047～1062行目は、上記以外の場合で、値を設定したり取得する場合の処理。input要素のtypeを変更しようとした場合には例外を発生させます。
1065～1081行目は、IEでopacityを扱う場合の処理です。
1083～1090行目は、属性名をキャメライズして、value引数が指定されていれば値を設定し、属性名値を返します。


以上でjQueryのコード全体の三分の一が終了しました。だいぶ全体像が見えてきたのではないかと思います。今回はクロスブラウザのためのバッドノウハウ的な部分が多く、泥臭い印象があったかもしれませんが、また次回をお楽しみに。