jQuery Access可以幫助我們操作DOM元素的屬性和樣式。以下是它的源代碼解析：

// Define access to element properties
jQuery.each({
attr: function( elem, name, value ) {
var ret, hooks,
nType = elem.nodeType;
// Don't get/set attributes on text, comment and attribute nodes
if ( nType === 3 || nType === 8 || nType === 2 ) {
return;
}
// Fallback to prop when attributes are not supported
if ( typeof elem.getAttribute === "undefined" ) {
return jQuery.prop( elem, name, value );
}
// Attribute hooks are determined by the lowercase version
// Grab necessary hook if one is defined
if ( nType !== 1 || !jQuery.isXMLDoc( elem ) ) {
hooks = jQuery.attrHooks[ name.toLowerCase() ] ||
( jQuery.expr.match.bool.test( name ) ? boolHook : undefined );
}
if ( value !== undefined ) {
if ( value === null ) {
jQuery.removeAttr( elem, name );
return;
}
if ( hooks && "set" in hooks &&
( ret = hooks.set( elem, value, name ) ) !== undefined ) {
return ret;
}
elem.setAttribute( name, value + "" );
return value;
}
if ( hooks && "get" in hooks && ( ret = hooks.get( elem, name ) ) !== null ) {
return ret;
}
ret = elem.getAttribute( name );
// Non-existent attributes return null, we normalize to undefined
return ret === null ? undefined : ret;
}
});
// Define attributes hook
jQuery.attrHooks = {
type: {
set: function( elem, value ) {
if ( !support.radioValue && value === "radio" &&
nodeName( elem, "input" ) ) {
var val = elem.value;
elem.setAttribute( "type", value );
if ( val ) {
elem.value = val;
}
return value;
}
}
}
};

這是一個比較復雜的源碼，通過定義函數(shù)和鉤子來完成常見的元素屬性和樣式的操作。比如，如果我們要獲取一個元素的屬性值，首先會判斷它的節(jié)點類型，容錯一些不支持getAttribute方法的情況，然后根據(jù)屬性名獲取對應的鉤子，最后如果有鉤子，則調用它來獲取屬性值；否則，直接調用getAttribute方法獲取屬性值。