jQuery部分源码注释——Sizzle（后续更新）
秦鹏飞
var Sizzle =
/*!
* Sizzle CSS Selector Engine v2.3.4
* https://sizzlejs.com/
*
* Copyright JS Foundation and other contributors
* Released under the MIT license
* https://js.foundation/
*
* Date: 2019-04-08
*/
(function( window ) {
var i,
support,
Expr,
getText,
isXML,
tokenize,
compile,
select,
outermostContext,
sortInput,
hasDuplicate,
// Local document vars
setDocument,
document,
docElem,
documentIsHTML,
rbuggyQSA,
rbuggyMatches,
matches,
contains,
// Instance-specific data
expando = "sizzle" + 1 * new Date(),
preferredDoc = window.document,
dirruns = 0,
done = 0,
classCache = createCache(),
tokenCache = createCache(),
compilerCache = createCache(),
nonnativeSelectorCache = createCache(),
sortOrder = function( a, b ) {
if ( a === b ) {
hasDuplicate = true;
}
return 0;
},
// Instance methods
hasOwn = ({}).hasOwnProperty,
arr = [],
pop = arr.pop,
push_native = arr.push,
push = arr.push,
slice = arr.slice,
// Use a stripped-down indexOf as it's faster than native
// https://jsperf.com/thor-indexof-vs-for/5
indexOf = function( list, elem ) {
var i = 0,
len = list.length;
//每一次循环时都会执行for里面的语句，多次重复调用Array.length会拖慢执行速度
for ( ; i < len; i++ ) {
if ( list[i] === elem ) {
return i;
}
}
return -1;
},
booleans = "checked|selected|async|autofocus|autoplay|controls|defer|disabled|hidden|ismap|loop|multiple|open|readonly|required|scoped",
// Regular expressions
// http://www.w3.org/TR/css3-selectors/#whitespace
whitespace = "[\\x20\\t\\r\\n\\f]",
// http://www.w3.org/TR/CSS21/syndata.html#value-def-identifier
identifier = "(?:\\\\.|[\\w-]|[^\0-\\xa0])+",
// Attribute selectors: http://www.w3.org/TR/selectors/#attribute-selectors
attributes = "\\[" + whitespace + "*(" + identifier + ")(?:" + whitespace +
// Operator (capture 2)
"*([*^$|!~]?=)" + whitespace +
// "Attribute values must be CSS identifiers [capture 5] or strings [capture 3 or capture 4]"
"*(?:'((?:\\\\.|[^\\\\'])*)'|\"((?:\\\\.|[^\\\\\"])*)\"|(" + identifier + "))|)" + whitespace +
"*\\]",
pseudos = ":(" + identifier + ")(?:\\((" +
// To reduce the number of selectors needing tokenize in the preFilter, prefer arguments:
// 1. quoted (capture 3; capture 4 or capture 5)
"('((?:\\\\.|[^\\\\'])*)'|\"((?:\\\\.|[^\\\\\"])*)\")|" +
// 2. simple (capture 6)
"((?:\\\\.|[^\\\\()[\\]]|" + attributes + ")*)|" +
// 3. anything else (capture 2)
".*" +
")\\)|)",
// Leading and non-escaped trailing whitespace, capturing some non-whitespace characters preceding the latter
rwhitespace = new RegExp( whitespace + "+", "g" ),
rtrim = new RegExp( "^" + whitespace + "+|((?:^|[^\\\\])(?:\\\\.)*)" + whitespace + "+$", "g" ),
rcomma = new RegExp( "^" + whitespace + "*," + whitespace + "*" ),
rcombinators = new RegExp( "^" + whitespace + "*([>+~]|" + whitespace + ")" + whitespace + "*" ),
rdescend = new RegExp( whitespace + "|>" ),
rpseudo = new RegExp( pseudos ),
ridentifier = new RegExp( "^" + identifier + "$" ),
matchExpr = {
"ID": new RegExp( "^#(" + identifier + ")" ),
"CLASS": new RegExp( "^\\.(" + identifier + ")" ),
"TAG": new RegExp( "^(" + identifier + "|[*])" ),
"ATTR": new RegExp( "^" + attributes ),
"PSEUDO": new RegExp( "^" + pseudos ),
"CHILD": new RegExp( "^:(only|first|last|nth|nth-last)-(child|of-type)(?:\\(" + whitespace +
"*(even|odd|(([+-]|)(\\d*)n|)" + whitespace + "*(?:([+-]|)" + whitespace +
"*(\\d+)|))" + whitespace + "*\\)|)", "i" ),
"bool": new RegExp( "^(?:" + booleans + ")$", "i" ),
// For use in libraries implementing .is()
// We use this for POS matching in `select`
"needsContext": new RegExp( "^" + whitespace + "*[>+~]|:(even|odd|eq|gt|lt|nth|first|last)(?:\\(" +
whitespace + "*((?:-\\d)?\\d*)" + whitespace + "*\\)|)(?=[^-]|$)", "i" )
},
rhtml = /HTML$/i,
rinputs = /^(?:input|select|textarea|button)$/i,
rheader = /^h\d$/i,
// 判断是否是native code，函数体内若是显示[native code]代表这个函数为计算机二进制内容，只能通过暴露的接口调用
// 也就是说这些函数不能够与bind或者call和apply使用
rnative = /^[^{]+\{\s*\[native \w/,
// Easily-parseable/retrievable ID or TAG or CLASS selectors
rquickExpr = /^(?:#([\w-]+)|(\w+)|\.([\w-]+))$/,
rsibling = /[+~]/,
// CSS escapes
// http://www.w3.org/TR/CSS21/syndata.html#escaped-characters
runescape = new RegExp( "\\\\([\\da-f]{1,6}" + whitespace + "?|(" + whitespace + ")|.)", "ig" ),
//转义16进制数，W3H允许在css中使用\开头的十六进制数（最多六位）来表示一些特殊符号，如果不足六位的话该十六进制数应当以任何形式的空白符结尾。
funescape = function( _, escaped, escapedWhitespace ) {
//需要判断该16进制数是遵循UTF-8规则（默认）还是其他的规则。
var high = "0x" + escaped - 0x10000;
// NaN means non-codepoint
// Support: Firefox<24
// Workaround erroneous numeric interpretation of +"0x"
return high !== high || escapedWhitespace ?
escaped :
high < 0 ?
// BMP codepoint
String.fromCharCode( high + 0x10000 ) :
// Supplemental Plane codepoint (surrogate pair)
String.fromCharCode( high >> 10 | 0xD800, high & 0x3FF | 0xDC00 );
},
// CSS string/identifier serialization
// https://drafts.csswg.org/cssom/#common-serializing-idioms
rcssescape = /([\0-\x1f\x7f]|^-?\d)|^-$|[^\0-\x1f\x7f-\uFFFF\w-]/g,
/**
* 该正则式用来查找特殊字符串对其按照标准进行序列化，详情参照上面的网页
* 这一步骤类似于词法分析器的一个预处理器，就是将扫描到的字符进行序列化，也就是转换为特殊的易于计算机识别的编码
**/
fcssescape = function( ch, asCodePoint ) {
if ( asCodePoint ) {
// U+0000 NULL becomes U+FFFD REPLACEMENT CHARACTER
if ( ch === "\0" ) {
return "\uFFFD";
}
// Control characters and (dependent upon position) numbers get escaped as code points
return ch.slice( 0, -1 ) + "\\" + ch.charCodeAt( ch.length - 1 ).toString( 16 ) + " ";
}
// Other potentially-special ASCII characters get backslash-escaped
return "\\" + ch;
},
// Used for iframes
// See setDocument()
// Removing the function wrapper causes a "Permission Denied"
// error in IE
unloadHandler = function() {
setDocument();
},
inDisabledFieldset = addCombinator(
function( elem ) {
return elem.disabled === true && elem.nodeName.toLowerCase() === "fieldset";
},
{ dir: "parentNode", next: "legend" }
);
// Optimize for push.apply( _, NodeList )
//测试原生的push方法的沙箱，不可用则重写
//在IE8及以下中，不支持aplly方法中的第二个参数是伪数组，所以在这里需要重写
try {
push.apply(
//类数组转数组
(arr = slice.call( preferredDoc.childNodes )),
preferredDoc.childNodes
);
// Support: Android<4.0
// Detect silently failing push.apply
arr[ preferredDoc.childNodes.length ].nodeType;
} catch ( e ) {
push = { apply: arr.length ?
// Leverage slice if possible
function( target, els ) {
push_native.apply( target, slice.call(els) );
} :
// Support: IE<9
// Otherwise append directly
function( target, els ) {
var j = target.length,
i = 0;
// Can't trust NodeList.length
// 当els[i]undefined的时候退出循环
while ( (target[j++] = els[i++]) ) {}
target.length = j - 1;
}
};
}
function Sizzle( selector, context, results, seed ) {
// selector是传入的正则表达式，context为筛选内容
var m, i, elem, nid, match, groups, newSelector,
newContext = context && context.ownerDocument,
// nodeType defaults to 9, since context defaults to document
nodeType = context ? context.nodeType : 9;
// 这里的初始化可以看出来这个函数是可以递归调用的
results = results || [];
// Return early from calls with invalid selector or context
if ( typeof selector !== "string" || !selector ||
nodeType !== 1 && nodeType !== 9 && nodeType !== 11 ) {
/** Typenode 含义
* 1 Element 代表元素 Element, Text, Comment, ProcessingInstruction, CDATASection, EntityReference
* 9 Document 代表整个文档（DOM 树的根节点）。 Element, ProcessingInstruction, Comment, DocumentType
* 11 DocumentFragment 代表轻量级的 Document 对象，能够容纳文档的某个部分 Element, ProcessingInstruction, Comment, Text, CDATASection, EntityReference
*/
return results;
}
// Try to shortcut find operations (as opposed to filters) in HTML documents
if ( !seed ) {
if ( ( context ? context.ownerDocument || context : preferredDoc ) !== document ) {
setDocument( context );
}
context = context || document;
if ( documentIsHTML ) {
// If the selector is sufficiently simple, try using a "get*By*" DOM method
// (excepting DocumentFragment context, where the methods don't exist)
if ( nodeType !== 11 && (match = rquickExpr.exec( selector )) ) {
// ID selector
// 如果为节点类型，为了返回值包括本身，需要获得parentNode
// 这主要是因为getElementById的运行机制，只返回第一个匹配值
if ( (m = match[1]) ) {
// Document context
if ( nodeType === 9 ) {
if ( (elem = context.getElementById( m )) ) {
// Support: IE, Opera, Webkit
// TODO: identify versions
// getElementById can match elements by name instead of ID
if ( elem.id === m ) {
results.push( elem );
return results;
}
} else {
return results;
}
// Element context
} else {
// Support: IE, Opera, Webkit
// TODO: identify versions
// getElementById can match elements by name instead of ID
if ( newContext && (elem = newContext.getElementById( m )) &&
contains( context, elem ) &&
elem.id === m ) {
results.push( elem );
return results;
}
}
// Type selector
} else if ( match[2] ) {
push.apply( results, context.getElementsByTagName( selector ) );
return results;
// Class selector
} else if ( (m = match[3]) && support.getElementsByClassName &&
context.getElementsByClassName ) {
push.apply( results, context.getElementsByClassName( m ) );
return results;
}
}
// Take advantage of querySelectorAll
if ( support.qsa &&
!nonnativeSelectorCache[ selector + " " ] &&
(!rbuggyQSA || !rbuggyQSA.test( selector )) &&
// rbuggyQSA是一个正则数组用来测试selector是否符合格式
// Support: IE 8 only
// Exclude object elements
(nodeType !== 1 || context.nodeName.toLowerCase() !== "object") ) {
newSelector = selector;
newContext = context;
// qSA considers elements outside a scoping root when evaluating child or
// descendant combinators, which is not what we want.
// In such cases, we work around the behavior by prefixing every selector in the
// list with an ID selector referencing the scope context.
// Thanks to Andrew Dupont for this technique.
if ( nodeType === 1 && rdescend.test( selector ) ) {
// Capture the context ID, setting it first if necessary
if ( (nid = context.getAttribute( "id" )) ) {
//将nid中的特殊符号序列化，转化为可识别的标识符
nid = nid.replace( rcssescape, fcssescape );
} else {
//随机生成一个id："sizzle" + 1 * new Date()
context.setAttribute( "id", (nid = expando) );
}
// Prefix every selector in the list
// 前面英文注释称qSA选择器会将不在范围内的符合条件的结果也一起作为结果返回
// 此处就是在每一个选择器的前面加入"#" + contentId来人为限定范围
// tokenize是一个定义在后面的词义分析器，输入为一个语句（string），输出为词义分析之后的token数组
groups = tokenize( selector );
i = groups.length;
while ( i-- ) {
groups[i] = "#" + nid + " " + toSelector( groups[i] );
}
newSelector = groups.join( "," );
// Expand context for sibling selectors
newContext = rsibling.test( selector ) && testContext( context.parentNode ) ||
context;
}
try {
push.apply( results,
newContext.querySelectorAll( newSelector )
);
return results;
} catch ( qsaError ) {
nonnativeSelectorCache( selector, true );
} finally {
if ( nid === expando ) { //这里去除了之前加入的临时随机ID
context.removeAttribute( "id" );
}
}
}
}
}
// All others
return select( selector.replace( rtrim, "$1" ), context, results, seed );
}
/**
* Create key-value caches of limited size
* @returns {function(string, object)} Returns the Object data after storing it on itself with
* property name the (space-suffixed) string and (if the cache is larger than Expr.cacheLength)
* deleting the oldest entry
*/
function createCache() {
//先进先出，队列机制
var keys = [];
function cache( key, value ) {
// Use (key + " ") to avoid collision with native prototype properties (see Issue #157)
if ( keys.push( key + " " ) > Expr.cacheLength ) {
// Only keep the most recent entries
delete cache[ keys.shift() ];
}
return (cache[ key + " " ] = value);
}
return cache;
}
/**
* Mark a function for special use by Sizzle
* @param {Function} fn The function to mark
* 为function添加一个特殊的随机命名的属性，在每次调用的时候校验，用来防止命名冲突
*/
function markFunction( fn ) {
fn[ expando ] = true;
return fn;
}
/**
* Support testing using an element
* @param {Function} fn Passed the created element and returns a boolean result
*/
function assert( fn ) {
var el = document.createElement("fieldset");
try {
return !!fn( el );
} catch (e) {
return false;
} finally {
// Remove from its parent by default
if ( el.parentNode ) {
el.parentNode.removeChild( el );
}
// release memory in IE
el = null;
}
}
/**
* Adds the same handler for all of the specified attrs
* @param {String} attrs Pipe-separated list of attributes
* @param {Function} handler The method that will be applied
*/
function addHandle( attrs, handler ) {
var arr = attrs.split("|"),
i = arr.length;
while ( i-- ) {
Expr.attrHandle[ arr[i] ] = handler;
}
}
/**
* Checks document order of two siblings
* 确定两个节点的出现顺序
* @param {Element} a
* @param {Element} b
* @returns {Number} Returns less than 0 if a precedes b, greater than 0 if a follows b
* 返回值小于零a先于b
*/
function siblingCheck( a, b ) {
var cur = b && a,
diff = cur && a.nodeType === 1 && b.nodeType === 1 &&
a.sourceIndex - b.sourceIndex;
// Use IE sourceIndex if available on both nodes
if ( diff ) {
return diff;
}
// Check if b follows a
// cur总是等于a，除非b传入false值。
// 前面cur的赋值语句顺序颠倒是早有安排，在阅读的时候应该意识到这一点
if ( cur ) {
while ( (cur = cur.nextSibling) ) {
if ( cur === b ) {
return -1;
}
}
}
// 如果a不为false值并且没有在上面的循环中返回，则a应当为b的儿子或者兄弟
// 如果a为false则返回-1
return a ? 1 : -1;
}
/**
* Returns a function to use in pseudos for input types
* 返回一个判断input类的种类的函数
* @param {String} type
*/
function createInputPseudo( type ) {
return function( elem ) {
var name = elem.nodeName.toLowerCase();
return name === "input" && elem.type === type;
};
}
/**
* Returns a function to use in pseudos for buttons
* 返回一个判断button伪类的函数，需要注意的是button也可以定义为input类型 type = button
* @param {String} type
*/
function createButtonPseudo( type ) {
return function( elem ) {
var name = elem.nodeName.toLowerCase();
return (name === "input" || name === "button") && elem.type === type;
};
}
/**
* Returns a function to use in pseudos for :enabled/:disabled
* @param {Boolean} disabled true for :disabled; false for :enabled
* 判断是否有enabled或者disabled伪类
*/
function createDisabledPseudo( disabled ) {
// Known :disabled false positives: fieldset[disabled] > legend:nth-of-type(n+2) :can-disable
return function( elem ) {
// Only certain elements can match :enabled or :disabled’
// 这两个伪类必须附着在 button, input, select, textarea, optgroup, option, fieldset或者是其他一些与表格相关的元素上
// https://html.spec.whatwg.org/multipage/scripting.html#selector-enabled
// https://html.spec.whatwg.org/multipage/scripting.html#selector-disabled
if ( "form" in elem ) {
// Check for inherited disabledness on relevant non-disabled elements:
// * listed form-associated elements in a disabled fieldset
// https://html.spec.whatwg.org/multipage/forms.html#category-listed
// https://html.spec.whatwg.org/multipage/forms.html#concept-fe-disabled
// * option elements in a disabled optgroup
// https://html.spec.whatwg.org/multipage/forms.html#concept-option-disabled
// button、fieldset、input、object、output、select、textarea、form-associated custom elements 复制于给出的网站
// All such elements have a "form" property.
if ( elem.parentNode && elem.disabled === false ) {
// Option elements defer to a parent optgroup if present
// 这类节点为disabled只在自己的disabled属性被设置为disabled
// 或者父节点为optgroup且它的disabled属性为disabled时
if ( "label" in elem ) {
if ( "label" in elem.parentNode ) {
return elem.parentNode.disabled === disabled;
} else {
return elem.disabled === disabled;
}
}
// Support: IE 6 - 11
// Use the isDisabled shortcut property to check for disabled fdieldset ancestors
return elem.isDisabled === disabled ||
// Where there is no isDisabled, check manually
/* jshint -W018 */
elem.isDisabled !== !disabled &&
inDisabledFieldset( elem ) === disabled;
}
return elem.disabled === disabled;
// Try to winnow out elements that can't be disabled before trusting the disabled property.
// Some victims get caught in our net (label, legend, menu, track), but it shouldn't
// even exist on them, let alone have a boolean value.
} else if ( "label" in elem ) {
return elem.disabled === disabled;
}
// Remaining elements are neither :enabled nor :disabled
return false;
};
}
/**
* Returns a function to use in pseudos for positionals
* @param {Function} fn
*/
function createPositionalPseudo( fn ) {
return markFunction(function( argument ) {
argument = +argument; //转数字
return markFunction(function( seed, matches ) {
var j,
matchIndexes = fn( [], seed.length, argument ),
i = matchIndexes.length;
// Match elements found at the specified indexes
while ( i-- ) {
if ( seed[ (j = matchIndexes[i]) ] ) {
seed[j] = !(matches[j] = seed[j]);
}
}
});
});
}
/**
* Checks a node for validity as a Sizzle context
* @param {Element|Object=} context
* @returns {Element|Object|Boolean} The input node if acceptable, otherwise a falsy value
*/
function testContext( context ) {
return context && typeof context.getElementsByTagName !== "undefined" && context;
}
// Expose support vars for convenience
support = Sizzle.support = {};
/**
* Detects XML nodes
* @param {Element|Object} elem An element or a document
* @returns {Boolean} True iff elem is a non-HTML XML node
*/
isXML = Sizzle.isXML = function( elem ) {
var namespace = elem.namespaceURI,
docElem = (elem.ownerDocument || elem).documentElement;
// Support: IE <=8
// Assume HTML when documentElement doesn't yet exist, such as inside loading iframes
// https://bugs.jquery.com/ticket/4833
return !rhtml.test( namespace || docElem && docElem.nodeName || "HTML" );
};
/**
* Sets document-related variables once based on the current document
* @param {Element|Object} [doc] An element or document object to use to set the document
* @returns {Object} Returns the current document
* 这里是主要的sizzle的与doc相关的属性的初始化代码
* 这里涉及到很多兼容性的代码
*/
setDocument = Sizzle.setDocument = function( node ) {
var hasCompare, subWindow,
doc = node ? node.ownerDocument || node : preferredDoc;
// Return early if doc is invalid or already selected
if ( doc === document || doc.nodeType !== 9 || !doc.documentElement ) {
return document;
}
// Update global variables
document = doc;
docElem = document.documentElement;
documentIsHTML = !isXML( document );
// Support: IE 9-11, Edge
// Accessing iframe documents after unload throws "permission denied" errors (jQuery #13936)
if ( preferredDoc !== document &&
(subWindow = document.defaultView) && subWindow.top !== subWindow ) {
// Support: IE 11, Edge
if ( subWindow.addEventListener ) {
subWindow.addEventListener( "unload", unloadHandler, false );
// Support: IE 9 - 10 only
} else if ( subWindow.attachEvent ) {
subWindow.attachEvent( "onunload", unloadHandler );
}
}
/* Attributes
---------------------------------------------------------------------- */
// Support: IE<8
// Verify that getAttribute really returns attributes and not properties
// (excepting IE8 booleans)
support.attributes = assert(function( el ) {
el.className = "i";
return !el.getAttribute("className");
});
/* getElement(s)By*
---------------------------------------------------------------------- */
// Check if getElementsByTagName("*") returns only elements
support.getElementsByTagName = assert(function( el ) {
el.appendChild( document.createComment("") );
return !el.getElementsByTagName("*").length;
});
// Support: IE<9
support.getElementsByClassName = rnative.test( document.getElementsByClassName );
// Support: IE<10
// Check if getElementById returns elements by name
// The broken getElementById methods don't pick up programmatically-set names,
// so use a roundabout getElementsByName test
support.getById = assert(function( el ) {
docElem.appendChild( el ).id = expando;
return !document.getElementsByName || !document.getElementsByName( expando ).length;
});
// ID filter and find
if ( support.getById ) {
Expr.filter["ID"] = function( id ) {
var attrId = id.replace( runescape, funescape );
return function( elem ) {
return elem.getAttribute("id") === attrId;
};
};
Expr.find["ID"] = function( id, context ) {
if ( typeof context.getElementById !== "undefined" && documentIsHTML ) {
var elem = context.getElementById( id );
return elem ? [ elem ] : [];
}
};
} else {
//属性节点是作为叶子节点接入DOM树的
Expr.filter["ID"] = function( id ) {
var attrId = id.replace( runescape, funescape );
return function( elem ) {
var node = typeof elem.getAttributeNode !== "undefined" &&
elem.getAttributeNode("id");
return node && node.value === attrId;
};
};
// Support: IE 6 - 7 only
// getElementById is not reliable as a find shortcut
// 不可靠是因为也会查找name
Expr.find["ID"] = function( id, context ) {
if ( typeof context.getElementById !== "undefined" && documentIsHTML ) {
var node, i, elems,
elem = context.getElementById( id );
if ( elem ) {
// Verify the id attribute
node = elem.getAttributeNode("id");
if ( node && node.value === id ) {
return [ elem ];
}
// Fall back on getElementsByName
elems = context.getElementsByName( id );
i = 0;
while ( (elem = elems[i++]) ) {
node = elem.getAttributeNode("id");
if ( node && node.value === id ) {
return [ elem ];
}
}
}
return [];
}
};
}
// Tag
Expr.find["TAG"] = support.getElementsByTagName ?
function( tag, context ) {
if ( typeof context.getElementsByTagName !== "undefined" ) {
return context.getElementsByTagName( tag );
// DocumentFragment nodes don't have gEBTN
} else if ( support.qsa ) {
return context.querySelectorAll( tag );
}
} :
function( tag, context ) {
var elem,
tmp = [],
i = 0,
// By happy coincidence, a (broken) gEBTN appears on DocumentFragment nodes too
results = context.getElementsByTagName( tag );
// Filter out possible comments
if ( tag === "*" ) {
while ( (elem = results[i++]) ) {
if ( elem.nodeType === 1 ) {
tmp.push( elem );
}
}
return tmp;
}
return results;
};
// Class
Expr.find["CLASS"] = support.getElementsByClassName && function( className, context ) {
if ( typeof context.getElementsByClassName !== "undefined" && documentIsHTML ) {
return context.getElementsByClassName( className );
}
};
/* QSA/matchesSelector
---------------------------------------------------------------------- */
// QSA and matchesSelector support
// matchesSelector(:active) reports false when true (IE9/Opera 11.5)
rbuggyMatches = [];
// qSa(:focus) reports false when true (Chrome 21)
// We allow this because of a bug in IE8/9 that throws an error
// whenever `document.activeElement` is accessed on an iframe
// So, we allow :focus to pass through QSA all the time to avoid the IE error
// See https://bugs.jquery.com/ticket/13378
rbuggyQSA = [];
if ( (support.qsa = rnative.test( document.querySelectorAll )) ) {
// Build QSA regex
// Regex strategy adopted from Diego Perini
assert(function( el ) {
// Select is set to empty string on purpose
// This is to test IE's treatment of not explicitly
// setting a boolean content attribute,
// since its presence should be enough
// https://bugs.jquery.com/ticket/12359
docElem.appendChild( el ).innerHTML = "<a id='" + expando + "'></a>" +
"<select id='" + expando + "-\r\\' msallowcapture=''>" +
"<option selected=''></option></select>";
// Support: IE8, Opera 11-12.16
// Nothing should be selected when empty strings follow ^= or $= or *=
// The test attribute must be unknown in Opera but "safe" for WinRT
// https://msdn.microsoft.com/en-us/library/ie/hh465388.aspx#attribute_section
if ( el.querySelectorAll("[msallowcapture^='']").length ) {
rbuggyQSA.push( "[*^$]=" + whitespace + "*(?:''|\"\")" );
}
// Support: IE8
// Boolean attributes and "value" are not treated correctly
if ( !el.querySelectorAll("[selected]").length ) {
rbuggyQSA.push( "\\[" + whitespace + "*(?:value|" + booleans + ")" );
}
// Support: Chrome<29, Android<4.4, Safari<7.0+, iOS<7.0+, PhantomJS<1.9.8+
if ( !el.querySelectorAll( "[id~=" + expando + "-]" ).length ) {
rbuggyQSA.push("~=");
}
// Webkit/Opera - :checked should return selected option elements
// http://www.w3.org/TR/2011/REC-css3-selectors-20110929/#checked
// IE8 throws error here and will not see later tests
if ( !el.querySelectorAll(":checked").length ) {
rbuggyQSA.push(":checked");
}
// Support: Safari 8+, iOS 8+
// https://bugs.webkit.org/show_bug.cgi?id=136851
// In-page `selector#id sibling-combinator selector` fails
if ( !el.querySelectorAll( "a#" + expando + "+*" ).length ) {
rbuggyQSA.push(".#.+[+~]");
}
});
assert(function( el ) {
el.innerHTML = "<a href='' disabled='disabled'></a>" +
"<select disabled='disabled'><option/></select>";
// Support: Windows 8 Native Apps
// The type and name attributes are restricted during .innerHTML assignment
var input = document.createElement("input");
input.setAttribute( "type", "hidden" );
el.appendChild( input ).setAttribute( "name", "D" );
// Support: IE8
// Enforce case-sensitivity of name attribute
if ( el.querySelectorAll("[name=d]").length ) {
rbuggyQSA.push( "name" + whitespace + "*[*^$|!~]?=" );
}
// FF 3.5 - :enabled/:disabled and hidden elements (hidden elements are still enabled)
// IE8 throws error here and will not see later tests
if ( el.querySelectorAll(":enabled").length !== 2 ) {
rbuggyQSA.push( ":enabled", ":disabled" );
}
// Support: IE9-11+
// IE's :disabled selector does not pick up the children of disabled fieldsets
docElem.appendChild( el ).disabled = true;
if ( el.querySelectorAll(":disabled").length !== 2 ) {
rbuggyQSA.push( ":enabled", ":disabled" );
}
// Opera 10-11 does not throw on post-comma invalid pseudos
el.querySelectorAll("*,:x");
rbuggyQSA.push(",.*:");
});
}
if ( (support.matchesSelector = rnative.test( (matches = docElem.matches ||
docElem.webkitMatchesSelector ||
docElem.mozMatchesSelector ||
docElem.oMatchesSelector ||
docElem.msMatchesSelector) )) ) {
assert(function( el ) {
// Check to see if it's possible to do matchesSelector
// on a disconnected node (IE 9)
support.disconnectedMatch = matches.call( el, "*" );
// This should fail with an exception
// Gecko does not error, returns false instead
matches.call( el, "[s!='']:x" );
rbuggyMatches.push( "!=", pseudos );
});
}
rbuggyQSA = rbuggyQSA.length && new RegExp( rbuggyQSA.join("|") );
rbuggyMatches = rbuggyMatches.length && new RegExp( rbuggyMatches.join("|") );
/** Contains
* 这里开头判断hasCompare，如果是[native code]可以认为是可靠的不会被其他custom函数覆盖的
* 这些函数因为函数体已经是二进制,用户尝试覆盖是会报错的，甚至不可以使用bind，call和apply
* 所以jQuery就可以直接调用，不得不说这样的验证的确非常严谨
---------------------------------------------------------------------- **/
hasCompare = rnative.test( docElem.compareDocumentPosition );
// Element contains another
// Purposefully self-exclusive
// As in, an element does not contain itself
contains = hasCompare || rnative.test( docElem.contains ) ?
function( a, b ) {
var adown = a.nodeType === 9 ? a.documentElement : a,
bup = b && b.parentNode;
return a === bup || !!( bup && bup.nodeType === 1 && (
adown.contains ?
adown.contains( bup ) :
// 这里使用了位运算，后面还会多次见到。
// 因为compareDocumentPosition返回值为0，2，4，8等值
// 对应二进制就是00000，00001，00010等值，所以只需要使用&就可以判断是否相等，
// & 这样的二进制位算符速度必定比 === 判断快得多（当然对这种小规模计算没有太多的效果）
// 类似于+-*/等等运算都需要经过全加器和选择器、有的还需要多次位移相加或者相减才能够得出结果
a.compareDocumentPosition && a.compareDocumentPosition( bup ) & 16
));
} :
function( a, b ) {
if ( b ) {
// 这段代码似曾相识啊
while ( (b = b.parentNode) ) {
if ( b === a ) {
return true;
}
}
}
return false;
};
/** Sorting
---------------------------------------------------------------------- **/
// Document order sorting
sortOrder = hasCompare ?
function( a, b ) {
// Flag for duplicate removal
if ( a === b ) {
hasDuplicate = true;
return 0;
}
// Sort on method existence if only one input has compareDocumentPosition
var compare = !a.compareDocumentPosition - !b.compareDocumentPosition;
if ( compare ) {
return compare;
}
// Calculate position if both inputs belong to the same document
compare = ( a.ownerDocument || a ) === ( b.ownerDocument || b ) ?
a.compareDocumentPosition( b ) :
// Otherwise we know they are disconnected
1;
// Disconnected nodes
if ( compare & 1 ||
(!support.sortDetached && b.compareDocumentPosition( a ) === compare) ) {
// Choose the first element that is related to our preferred document
if ( a === document || a.ownerDocument === preferredDoc && contains(preferredDoc, a) ) {
return -1;
}
if ( b === document || b.ownerDocument === preferredDoc && contains(preferredDoc, b) ) {
return 1;
}
// Maintain original order
return sortInput ?
( indexOf( sortInput, a ) - indexOf( sortInput, b ) ) :
0;
}
return compare & 4 ? -1 : 1;
} :
function( a, b ) {
// Exit early if the nodes are identical
if ( a === b ) {
hasDuplicate = true;
return 0;
}
var cur,
i = 0,
aup = a.parentNode,
bup = b.parentNode,
ap = [ a ],
bp = [ b ];
// Parentless nodes are either documents or disconnected
if ( !aup || !bup ) {
return a === document ? -1 :
b === document ? 1 :
aup ? -1 :
bup ? 1 :
sortInput ?
( indexOf( sortInput, a ) - indexOf( sortInput, b ) ) :
0;
// If the nodes are siblings, we can do a quick check
} else if ( aup === bup ) {
return siblingCheck( a, b );
}
// Otherwise we need full lists of their ancestors for comparison
cur = a;
while ( (cur = cur.parentNode) ) {
ap.unshift( cur );
}
cur = b;
while ( (cur = cur.parentNode) ) {
bp.unshift( cur );
}
// Walk down the tree looking for a discrepancy
while ( ap[i] === bp[i] ) {
i++;
}
return i ?
// Do a sibling check if the nodes have a common ancestor
siblingCheck( ap[i], bp[i] ) :
// Otherwise nodes in our document sort first
ap[i] === preferredDoc ? -1 :
bp[i] === preferredDoc ? 1 :
0;
};
return document;
};
Sizzle.matches = function( expr, elements ) {
// 返回匹配的Sizzle对象
return Sizzle( expr, null, null, elements );
};
Sizzle.matchesSelector = function( elem, expr ) {
// Set document vars if needed
// 兼容封装
if ( ( elem.ownerDocument || elem ) !== document ) {
setDocument( elem );
}
if ( support.matchesSelector && documentIsHTML &&
!nonnativeSelectorCache[ expr + " " ] &&
( !rbuggyMatches || !rbuggyMatches.test( expr ) ) &&
( !rbuggyQSA || !rbuggyQSA.test( expr ) ) ) {
try {
var ret = matches.call( elem, expr );
// IE 9's matchesSelector returns false on disconnected nodes
if ( ret || support.disconnectedMatch ||
// As well, disconnected nodes are said to be in a document
// fragment in IE 9
elem.document && elem.document.nodeType !== 11 ) {
return ret;
}
} catch (e) {
nonnativeSelectorCache( expr, true );
}
}
return Sizzle( expr, document, null, [ elem ] ).length > 0;
};
Sizzle.contains = function( context, elem ) {
// Set document vars if needed
if ( ( context.ownerDocument || context ) !== document ) {
setDocument( context );
}
return contains( context, elem );
};
Sizzle.attr = function( elem, name ) {
// 获取指定的属性的属性值，自带的getAttribute
// Set document vars if needed
if ( ( elem.ownerDocument || elem ) !== document ) {
setDocument( elem );
}
var fn = Expr.attrHandle[ name.toLowerCase() ],
// Don't get fooled by Object.prototype properties (jQuery #13807)
val = fn && hasOwn.call( Expr.attrHandle, name.toLowerCase() ) ?
fn( elem, name, !documentIsHTML ) :
undefined;
return val !== undefined ?
val :
support.attributes || !documentIsHTML ?
elem.getAttribute( name ) :
(val = elem.getAttributeNode(name)) && val.specified ?
val.value :
null;
};
Sizzle.escape = function( sel ) {
// 封装了前面的函数和正则式，可以对给定的CSS进行预处理
return (sel + "").replace( rcssescape, fcssescape );
};
Sizzle.error = function( msg ) {
throw new Error( "Syntax error, unrecognized expression: " + msg );
};
/**
* Document sorting and removing duplicates
* @param {ArrayLike} results
*/
Sizzle.uniqueSort = function( results ) {
var elem,
duplicates = [],
j = 0,
i = 0;
// Unless we *know* we can detect duplicates, assume their presence
hasDuplicate = !support.detectDuplicates;
sortInput = !support.sortStable && results.slice( 0 );
results.sort( sortOrder );
if ( hasDuplicate ) {
// 这个循环对比的写法很有意思，++运算符果然乐趣无穷
while ( (elem = results[i++]) ) {
if ( elem === results[ i ] ) {
j = duplicates.push( i );
}
}
while ( j-- ) {
results.splice( duplicates[ j ], 1 );
}
}
// Clear input after sorting to release objects
// See https://github.com/jquery/sizzle/pull/225
// 因为sortInput作为闭包里的变量不会被内存回收机制立即回收
// 所以在多次调用到Sizzle的时候，sortInput的内容会被复制出多个副本最终导致内存溢出
// 置空并没有根本上解决这个问题，只是让sortInput占用空间变小而已
sortInput = null;
return results;
};
/**
* Utility function for retrieving the text value of an array of DOM nodes
* @param {Array|Element} elem
*/
getText = Sizzle.getText = function( elem ) {
var node,
ret = "",
i = 0,
nodeType = elem.nodeType;
if ( !nodeType ) {
// If no nodeType, this is expected to be an array
while ( (node = elem[i++]) ) {
// Do not traverse comment nodes
// 避开注释节点
ret += getText( node );
}
} else if ( nodeType === 1 || nodeType === 9 || nodeType === 11 ) {
// Use textContent for elements
// innerText usage removed for consistency of new lines (jQuery #11153)
// textContent会根据标签里面的元素独立一行
// innerText不会理会html格式，直接输出不换行的文本
// textContent 会获取style= “display:none” 中的文本，而innerText不会
if ( typeof elem.textContent === "string" ) {
return elem.textContent;
} else {
// Traverse its children
for ( elem = elem.firstChild; elem; elem = elem.nextSibling ) {
ret += getText( elem );
}
}
} else if ( nodeType === 3 || nodeType === 4 ) {
// 3 Text 代表元素或属性中的文本内容。
// 4 CDATASection 代表文档中的 CDATA 部分（不会由解析器解析的文本）。
return elem.nodeValue;
}
// Do not include comment or processing instruction nodes
return ret;
};
Expr = Sizzle.selectors = {
// Can be adjusted by the user
cacheLength: 50,
createPseudo: markFunction,
match: matchExpr,
/**
* matchExpr = {
"ID": new RegExp( "^#(" + identifier + ")" ),
"CLASS": new RegExp( "^\\.(" + identifier + ")" ),
"TAG": new RegExp( "^(" + identifier + "|[*])" ),
"ATTR": new RegExp( "^" + attributes ),
"PSEUDO": new RegExp( "^" + pseudos ),
"CHILD": new RegExp( "^:(only|first|last|nth|nth-last)-(child|of-type)(?:\\(" + whitespace +
"*(even|odd|(([+-]|)(\\d*)n|)" + whitespace + "*(?:([+-]|)" + whitespace +
"*(\\d+)|))" + whitespace + "*\\)|)", "i" ),
"bool": new RegExp( "^(?:" + booleans + ")$", "i" ),
// For use in libraries implementing .is()
// We use this for POS matching in `select`
"needsContext": new RegExp( "^" + whitespace + "*[>+~]|:(even|odd|eq|gt|lt|nth|first|last)(?:\\(" +
whitespace + "*((?:-\\d)?\\d*)" + whitespace + "*\\)|)(?=[^-]|$)", "i" )
},
*/
attrHandle: {},
find: {},
relative: {
">": { dir: "parentNode", first: true },
" ": { dir: "parentNode" },
"+": { dir: "previousSibling", first: true },
"~": { dir: "previousSibling" }
},
// preFilter这里主要将一些类型进行简单的类型检查和转换
// 属于词义分析的一个前置转换，统一格式方便后面filter
preFilter: {
"ATTR": function( match ) {
match[1] = match[1].replace( runescape, funescape );
// Move the given value to match[3] whether quoted or unquoted
match[3] = ( match[3] || match[4] || match[5] || "" ).replace( runescape, funescape );
if ( match[2] === "~=" ) {
match[3] = " " + match[3] + " ";
}
return match.slice( 0, 4 );
},
"CHILD": function( match ) {
/* matches from matchExpr["CHILD"]
1 type (only|nth|...)
2 what (child|of-type)
3 argument (even|odd|\d*|\d*n([+-]\d+)?|...)
4 xn-component of xn+y argument ([+-]?\d*n|)
5 sign of xn-component
6 x of xn-component
7 sign of y-component
8 y of y-component
*/
match[1] = match[1].toLowerCase();
if ( match[1].slice( 0, 3 ) === "nth" ) {
// nth-* requires argument
if ( !match[3] ) {
Sizzle.error( match[0] );
}
// numeric x and y parameters for Expr.filter.CHILD
// remember that false/true cast respectively to 0/1
match[4] = +( match[4] ? match[5] + (match[6] || 1) : 2 * ( match[3] === "even" || match[3] === "odd" ) );
match[5] = +( ( match[7] + match[8] ) || match[3] === "odd" );
// other types prohibit arguments
} else if ( match[3] ) {
Sizzle.error( match[0] );
}
return match;
},
"PSEUDO": function( match ) {
var excess,
unquoted = !match[6] && match[2];
if ( matchExpr["CHILD"].test( match[0] ) ) {
return null;
}
// Accept quoted arguments as-is
if ( match[3] ) {
match[2] = match[4] || match[5] || "";
// Strip excess characters from unquoted arguments
} else if ( unquoted && rpseudo.test( unquoted ) &&
// Get excess from tokenize (recursively)
(excess = tokenize( unquoted, true )) &&
// advance to the next closing parenthesis
(excess = unquoted.indexOf( ")", unquoted.length - excess ) - unquoted.length) ) {
// excess is a negative index
match[0] = match[0].slice( 0, excess );
match[2] = unquoted.slice( 0, excess );
}
// Return only captures needed by the pseudo filter method (type and argument)
return match.slice( 0, 3 );
}
},
filter: {
"TAG": function( nodeNameSelector ) {
var nodeName = nodeNameSelector.replace( runescape, funescape ).toLowerCase();
return nodeNameSelector === "*" ?
function() { return true; } :
function( elem ) {
return elem.nodeName && elem.nodeName.toLowerCase() === nodeName;
};
},
"CLASS": function( className ) {
var pattern = classCache[ className + " " ];
return pattern ||
(pattern = new RegExp( "(^|" + whitespace + ")" + className + "(" + whitespace + "|$)" )) &&
classCache( className, function( elem ) {
return pattern.test( typeof elem.className === "string" && elem.className || typeof elem.getAttribute !== "undefined" && elem.getAttribute("class") || "" );
});
},
"ATTR": function( name, operator, check ) {
return function( elem ) {
var result = Sizzle.attr( elem, name );
if ( result == null ) {
return operator === "!=";
}
if ( !operator ) {
return true;
}
result += "";
return operator === "=" ? result === check :
operator === "!=" ? result !== check :
operator === "^=" ? check && result.indexOf( check ) === 0 :
operator === "*=" ? check && result.indexOf( check ) > -1 :
operator === "$=" ? check && result.slice( -check.length ) === check :
operator === "~=" ? ( " " + result.replace( rwhitespace, " " ) + " " ).indexOf( check ) > -1 :
operator === "|=" ? result === check || result.slice( 0, check.length + 1 ) === check + "-" :
false;
};
},
"CHILD": function( type, what, argument, first, last ) {
var simple = type.slice( 0, 3 ) !== "nth",
forward = type.slice( -4 ) !== "last",
ofType = what === "of-type";
return first === 1 && last === 0 ?
// Shortcut for :nth-*(n)
function( elem ) {
return !!elem.parentNode;
} :
function( elem, context, xml ) {
var cache, uniqueCache, outerCache, node, nodeIndex, start,
dir = simple !== forward ? "nextSibling" : "previousSibling",
parent = elem.parentNode,
name = ofType && elem.nodeName.toLowerCase(),
useCache = !xml && !ofType,
diff = false;
if ( parent ) {
// :(first|last|only)-(child|of-type)
if ( simple ) {
while ( dir ) {
node = elem;
while ( (node = node[ dir ]) ) {
if ( ofType ?
node.nodeName.toLowerCase() === name :
node.nodeType === 1 ) {
return false;
}
}
// Reverse direction for :only-* (if we haven't yet done so)
start = dir = type === "only" && !start && "nextSibling";
}
return true;
}
start = [ forward ? parent.firstChild : parent.lastChild ];
// non-xml :nth-child(...) stores cache data on `parent`
if ( forward && useCache ) {
// Seek `elem` from a previously-cached index
// ...in a gzip-friendly way
node = parent;
outerCache = node[ expando ] || (node[ expando ] = {});
// Support: IE <9 only
// Defend against cloned attroperties (jQuery gh-1709)
uniqueCache = outerCache[ node.uniqueID ] ||
(outerCache[ node.uniqueID ] = {});
cache = uniqueCache[ type ] || [];
nodeIndex = cache[ 0 ] === dirruns && cache[ 1 ];
diff = nodeIndex && cache[ 2 ];
node = nodeIndex && parent.childNodes[ nodeIndex ];
while ( (node = ++nodeIndex && node && node[ dir ] ||
// Fallback to seeking `elem` from the start
(diff = nodeIndex = 0) || start.pop()) ) {
// When found, cache indexes on `parent` and break
if ( node.nodeType === 1 && ++diff && node === elem ) {
uniqueCache[ type ] = [ dirruns, nodeIndex, diff ];
break;
}
}
} else {
// Use previously-cached element index if available
if ( useCache ) {
// ...in a gzip-friendly way
node = elem;
outerCache = node[ expando ] || (node[ expando ] = {});
// Support: IE <9 only
// Defend against cloned attroperties (jQuery gh-1709)
uniqueCache = outerCache[ node.uniqueID ] ||
(outerCache[ node.uniqueID ] = {});
cache = uniqueCache[ type ] || [];
nodeIndex = cache[ 0 ] === dirruns && cache[ 1 ];
diff = nodeIndex;
}
// xml :nth-child(...)
// or :nth-last-child(...) or :nth(-last)?-of-type(...)
if ( diff === false ) {
// Use the same loop as above to seek `elem` from the start
while ( (node = ++nodeIndex && node && node[ dir ] ||
(diff = nodeIndex = 0) || start.pop()) ) {
if ( ( ofType ?
node.nodeName.toLowerCase() === name :
node.nodeType === 1 ) &&
++diff ) {
// Cache the index of each encountered element
if ( useCache ) {
outerCache = node[ expando ] || (node[ expando ] = {});
// Support: IE <9 only
// Defend against cloned attroperties (jQuery gh-1709)
uniqueCache = outerCache[ node.uniqueID ] ||
(outerCache[ node.uniqueID ] = {});
uniqueCache[ type ] = [ dirruns, diff ];
}
if ( node === elem ) {
break;
}
}
}
}
}
// Incorporate the offset, then check against cycle size
diff -= last;
return diff === first || ( diff % first === 0 && diff / first >= 0 );
}
};
},
"PSEUDO": function( pseudo, argument ) {
// pseudo-class names are case-insensitive
// http://www.w3.org/TR/selectors/#pseudo-classes
// Prioritize by case sensitivity in case custom pseudos are added with uppercase letters
// Remember that setFilters inherits from pseudos
var args,
fn = Expr.pseudos[ pseudo ] || Expr.setFilters[ pseudo.toLowerCase() ] ||
Sizzle.error( "unsupported pseudo: " + pseudo );
// The user may use createPseudo to indicate that
// arguments are needed to create the filter function
// just as Sizzle does
if ( fn[ expando ] ) {
return fn( argument );
}
// But maintain support for old signatures
if ( fn.length > 1 ) {
args = [ pseudo, pseudo, "", argument ];
return Expr.setFilters.hasOwnProperty( pseudo.toLowerCase() ) ?
markFunction(function( seed, matches ) {
var idx,
matched = fn( seed, argument ),
i = matched.length;
while ( i-- ) {
idx = indexOf( seed, matched[i] );
seed[ idx ] = !( matches[ idx ] = matched[i] );
}
}) :
function( elem ) {
return fn( elem, 0, args );
};
}
return fn;
}
},
pseudos: {
// Potentially complex pseudos
"not": markFunction(function( selector ) {
// Trim the selector passed to compile
// to avoid treating leading and trailing
// spaces as combinators
var input = [],
results = [],
matcher = compile( selector.replace( rtrim, "$1" ) );
return matcher[ expando ] ?
markFunction(function( seed, matches, context, xml ) {
var elem,
unmatched = matcher( seed, null, xml, [] ),
i = seed.length;
// Match elements unmatched by `matcher`
while ( i-- ) {
if ( (elem = unmatched[i]) ) {
seed[i] = !(matches[i] = elem);
}
}
}) :
function( elem, context, xml ) {
input[0] = elem;
matcher( input, null, xml, results );
// Don't keep the element (issue #299)
input[0] = null;
return !results.pop();
};
}),
"has": markFunction(function( selector ) {
return function( elem ) {
return Sizzle( selector, elem ).length > 0;
};
}),
"contains": markFunction(function( text ) {
text = text.replace( runescape, funescape );
return function( elem ) {
return ( elem.textContent || getText( elem ) ).indexOf( text ) > -1;
};
}),
// "Whether an element is represented by a :lang() selector
// is based solely on the element's language value
// being equal to the identifier C,
// or beginning with the identifier C immediately followed by "-".
// The matching of C against the element's language value is performed case-insensitively.
// The identifier C does not have to be a valid language name."
// http://www.w3.org/TR/selectors/#lang-pseudo
"lang": markFunction( function( lang ) {
// lang value must be a valid identifier
if ( !ridentifier.test(lang || "") ) {
Sizzle.error( "unsupported lang: " + lang );
}
lang = lang.replace( runescape, funescape ).toLowerCase();
return function( elem ) {
var elemLang;
do {
if ( (elemLang = documentIsHTML ?
elem.lang :
elem.getAttribute("xml:lang") || elem.getAttribute("lang")) ) {
elemLang = elemLang.toLowerCase();
return elemLang === lang || elemLang.indexOf( lang + "-" ) === 0;
}
} while ( (elem = elem.parentNode) && elem.nodeType === 1 );
return false;
};
}),
// Miscellaneous
"target": function( elem ) {
var hash = window.location && window.location.hash;
return hash && hash.slice( 1 ) === elem.id;
},
"root": function( elem ) {
return elem === docElem;
},
"focus": function( elem ) {
return elem === document.activeElement && (!document.hasFocus || document.hasFocus()) && !!(elem.type || elem.href || ~elem.tabIndex);
},
// Boolean properties
"enabled": createDisabledPseudo( false ),
"disabled": createDisabledPseudo( true ),
"checked": function( elem ) {
// In CSS3, :checked should return both checked and selected elements
// http://www.w3.org/TR/2011/REC-css3-selectors-20110929/#checked
var nodeName = elem.nodeName.toLowerCase();
return (nodeName === "input" && !!elem.checked) || (nodeName === "option" && !!elem.selected);
},
"selected": function( elem ) {
// Accessing this property makes selected-by-default
// options in Safari work properly
if ( elem.parentNode ) {
elem.parentNode.selectedIndex;
}
return elem.selected === true;
},
// Contents
"empty": function( elem ) {
// http://www.w3.org/TR/selectors/#empty-pseudo
// :empty is negated by element (1) or content nodes (text: 3; cdata: 4; entity ref: 5),
// but not by others (comment: 8; processing instruction: 7; etc.)
// nodeType < 6 works because attributes (2) do not appear as children
for ( elem = elem.firstChild; elem; elem = elem.nextSibling ) {
if ( elem.nodeType < 6 ) {
return false;
}
}
return true;
},
"parent": function( elem ) {
return !Expr.pseudos["empty"]( elem );
},
// Element/input types
"header": function( elem ) {
return rheader.test( elem.nodeName );
},
"input": function( elem ) {
return rinputs.test( elem.nodeName );
},
"button": function( elem ) {
var name = elem.nodeName.toLowerCase();
return name === "input" && elem.type === "button" || name === "button";
},
"text": function( elem ) {
var attr;
return elem.nodeName.toLowerCase() === "input" &&
elem.type === "text" &&
// Support: IE<8
// New HTML5 attribute values (e.g., "search") appear with elem.type === "text"
( (attr = elem.getAttribute("type")) == null || attr.toLowerCase() === "text" );
},
// Position-in-collection
"first": createPositionalPseudo(function() {
return [ 0 ];
}),
"last": createPositionalPseudo(function( matchIndexes, length ) {
return [ length - 1 ];
}),
"eq": createPositionalPseudo(function( matchIndexes, length, argument ) {
return [ argument < 0 ? argument + length : argument ];
}),
"even": createPositionalPseudo(function( matchIndexes, length ) {
var i = 0;
for ( ; i < length; i += 2 ) {
matchIndexes.push( i );
}
return matchIndexes;
}),
"odd": createPositionalPseudo(function( matchIndexes, length ) {
var i = 1;
for ( ; i < length; i += 2 ) {
matchIndexes.push( i );
}
return matchIndexes;
}),
"lt": createPositionalPseudo(function( matchIndexes, length, argument ) {
var i = argument < 0 ?
argument + length :
argument > length ?
length :
argument;
for ( ; --i >= 0; ) {
matchIndexes.push( i );
}
return matchIndexes;
}),
"gt": createPositionalPseudo(function( matchIndexes, length, argument ) {
var i = argument < 0 ? argument + length : argument;
for ( ; ++i < length; ) {
matchIndexes.push( i );
}
return matchIndexes;
})
}
};
Expr.pseudos["nth"] = Expr.pseudos["eq"];
// Add button/input type pseudos
for ( i in { radio: true, checkbox: true, file: true, password: true, image: true } ) {
Expr.pseudos[ i ] = createInputPseudo( i );
}
for ( i in { submit: true, reset: true } ) {
Expr.pseudos[ i ] = createButtonPseudo( i );
}
// Easy API for creating new setFilters
function setFilters() {}
setFilters.prototype = Expr.filters = Expr.pseudos;
Expr.setFilters = new setFilters();
// 词法分析器的顶层函数，
// 将传入的选择器字符串转换为token键值对数组，标识不同的单词类型。
// 这里需要结合css的选择器和伪类的词法结构来看
tokenize = Sizzle.tokenize = function( selector, parseOnly ) {
var matched, match, tokens, type,
soFar, groups, preFilters,
cached = tokenCache[ selector + " " ];
if ( cached ) {
return parseOnly ? 0 : cached.slice( 0 );
}
soFar = selector;
groups = [];
preFilters = Expr.preFilter;
// 每次识别一个单词或者符号，辨别其属性压入tokens中最后压入groups
while ( soFar ) {
// Comma and first run
// 识别逗号，遇到逗号就将前面的符号加入数组
if ( !matched || (match = rcomma.exec( soFar )) ) {
if ( match ) {
// Don't consume trailing commas as valid
soFar = soFar.slice( match[0].length ) || soFar;
}
groups.push( (tokens = []) );
}
matched = false;
// Combinators
//查找>+~
if ( (match = rcombinators.exec( soFar )) ) {
matched = match.shift();
tokens.push({
value: matched,
// Cast descendant combinators to space
type: match[0].replace( rtrim, " " )
});
soFar = soFar.slice( matched.length );
}
// 一类类的查找识别当前字符属于哪一类，填入对应的键值对中
// Filters
for ( type in Expr.filter ) {
if ( (match = matchExpr[ type ].exec( soFar )) && (!preFilters[ type ] ||
(match = preFilters[ type ]( match ))) ) {
matched = match.shift();
tokens.push({
value: matched,
type: type,
matches: match
});
soFar = soFar.slice( matched.length );
}
}
if ( !matched ) {
break;
}
}
// Return the length of the invalid excess
// if we're just parsing
// Otherwise, throw an error or return tokens
return parseOnly ?
soFar.length :
soFar ?
Sizzle.error( selector ) :
// Cache the tokens
tokenCache( selector, groups ).slice( 0 );
};
function toSelector( tokens ) {
var i = 0,
len = tokens.length,
selector = "";
for ( ; i < len; i++ ) {
selector += tokens[i].value;
}
return selector;
}
function addCombinator( matcher, combinator, base ) {
var dir = combinator.dir,
skip = combinator.next,
key = skip || dir,
//这一句虽然判断语句在后面，但是如果判断语句为false整句仍为false，前面的赋值语句也不会执行
checkNonElements = base && key === "parentNode",
doneName = done++;
return combinator.first ?
// Check against closest ancestor/preceding element
function( elem, context, xml ) {
while ( (elem = elem[ dir ]) ) {
if ( elem.nodeType === 1 || checkNonElements ) {
return matcher( elem, context, xml );
}
}
return false;
} :
// Check against all ancestor/preceding elements
function( elem, context, xml ) {
var oldCache, uniqueCache, outerCache,
newCache = [ dirruns, doneName ];
// We can't set arbitrary data on XML nodes, so they don't benefit from combinator caching
if ( xml ) {
while ( (elem = elem[ dir ]) ) {
if ( elem.nodeType === 1 || checkNonElements ) {
if ( matcher( elem, context, xml ) ) {
return true;
}
}
}
} else {
while ( (elem = elem[ dir ]) ) {
if ( elem.nodeType === 1 || checkNonElements ) {
outerCache = elem[ expando ] || (elem[ expando ] = {});
// Support: IE <9 only
// Defend against cloned attroperties (jQuery gh-1709)
uniqueCache = outerCache[ elem.uniqueID ] || (outerCache[ elem.uniqueID ] = {});
if ( skip && skip === elem.nodeName.toLowerCase() ) {
elem = elem[ dir ] || elem;
} else if ( (oldCache = uniqueCache[ key ]) &&
oldCache[ 0 ] === dirruns && oldCache[ 1 ] === doneName ) {
// Assign to newCache so results back-propagate to previous elements
return (newCache[ 2 ] = oldCache[ 2 ]);
} else {
// Reuse newcache so results back-propagate to previous elements
uniqueCache[ key ] = newCache;
// A match means we're done; a fail means we have to keep checking
if ( (newCache[ 2 ] = matcher( elem, context, xml )) ) {
return true;
}
}
}
}
}
return false;
};
}
function elementMatcher( matchers ) {
return matchers.length > 1 ?
function( elem, context, xml ) {
var i = matchers.length;
while ( i-- ) {
if ( !matchers[i]( elem, context, xml ) ) {
return false;
}
}
return true;
} :
matchers[0];
}
function multipleContexts( selector, contexts, results ) {
var i = 0,
len = contexts.length;
for ( ; i < len; i++ ) {
Sizzle( selector, contexts[i], results );
}
return results;
}
function condense( unmatched, map, filter, context, xml ) {
var elem,
newUnmatched = [],
i = 0,
len = unmatched.length,
mapped = map != null;
for ( ; i < len; i++ ) {
if ( (elem = unmatched[i]) ) {
if ( !filter || filter( elem, context, xml ) ) {
newUnmatched.push( elem );
if ( mapped ) {
map.push( i );
}
}
}
}
return newUnmatched;
}
function setMatcher( preFilter, selector, matcher, postFilter, postFinder, postSelector ) {
if ( postFilter && !postFilter[ expando ] ) {
postFilter = setMatcher( postFilter );
}
if ( postFinder && !postFinder[ expando ] ) {
postFinder = setMatcher( postFinder, postSelector );
}
return markFunction(function( seed, results, context, xml ) {
var temp, i, elem,
preMap = [],
postMap = [],
preexisting = results.length,
// Get initial elements from seed or context
elems = seed || multipleContexts( selector || "*", context.nodeType ? [ context ] : context, [] ),
// Prefilter to get matcher input, preserving a map for seed-results synchronization
matcherIn = preFilter && ( seed || !selector ) ?
condense( elems, preMap, preFilter, context, xml ) :
elems,
matcherOut = matcher ?
// If we have a postFinder, or filtered seed, or non-seed postFilter or preexisting results,
postFinder || ( seed ? preFilter : preexisting || postFilter ) ?
// ...intermediate processing is necessary
[] :
// ...otherwise use results directly
results :
matcherIn;
// Find primary matches
if ( matcher ) {
matcher( matcherIn, matcherOut, context, xml );
}
// Apply postFilter
if ( postFilter ) {
temp = condense( matcherOut, postMap );
postFilter( temp, [], context, xml );
// Un-match failing elements by moving them back to matcherIn
i = temp.length;
while ( i-- ) {
if ( (elem = temp[i]) ) {
matcherOut[ postMap[i] ] = !(matcherIn[ postMap[i] ] = elem);
}
}
}
if ( seed ) {
if ( postFinder || preFilter ) {
if ( postFinder ) {
// Get the final matcherOut by condensing this intermediate into postFinder contexts
temp = [];
i = matcherOut.length;
while ( i-- ) {
if ( (elem = matcherOut[i]) ) {
// Restore matcherIn since elem is not yet a final match
temp.push( (matcherIn[i] = elem) );
}
}
postFinder( null, (matcherOut = []), temp, xml );
}
// Move matched elements from seed to results to keep them synchronized
i = matcherOut.length;
while ( i-- ) {
if ( (elem = matcherOut[i]) &&
(temp = postFinder ? indexOf( seed, elem ) : preMap[i]) > -1 ) {
seed[temp] = !(results[temp] = elem);
}
}
}
// Add elements to results, through postFinder if defined
} else {
matcherOut = condense(
matcherOut === results ?
matcherOut.splice( preexisting, matcherOut.length ) :
matcherOut
);
if ( postFinder ) {
postFinder( null, results, matcherOut, xml );
} else {
push.apply( results, matcherOut );
}
}
});
}
/**
* 该函数主要为了将符号化的选择器数组
* @param {*} tokens
*/
function matcherFromTokens( tokens ) {
var checkContext, matcher, j,
len = tokens.length,
leadingRelative = Expr.relative[ tokens[0].type ],
implicitRelative = leadingRelative || Expr.relative[" "],
i = leadingRelative ? 1 : 0,
// The foundational matcher ensures that elements are reachable from top-level context(s)
matchContext = addCombinator( function( elem ) {
return elem === checkContext;
}, implicitRelative, true ),
matchAnyContext = addCombinator( function( elem ) {
return indexOf( checkContext, elem ) > -1;
}, implicitRelative, true ),
matchers = [ function( elem, context, xml ) {
var ret = ( !leadingRelative && ( xml || context !== outermostContext ) ) || (
(checkContext = context).nodeType ?
matchContext( elem, context, xml ) :
matchAnyContext( elem, context, xml ) );
// Avoid hanging onto element (issue #299)
checkContext = null;
return ret;
} ];
for ( ; i < len; i++ ) {
if ( (matcher = Expr.relative[ tokens[i].type ]) ) {
matchers = [ addCombinator(elementMatcher( matchers ), matcher) ];
} else {
matcher = Expr.filter[ tokens[i].type ].apply( null, tokens[i].matches );
// Return special upon seeing a positional matcher
if ( matcher[ expando ] ) {
// Find the next relative operator (if any) for proper handling
j = ++i;
for ( ; j < len; j++ ) {
if ( Expr.relative[ tokens[j].type ] ) {
break;
}
}
return setMatcher(
i > 1 && elementMatcher( matchers ),
i > 1 && toSelector(
// If the preceding token was a descendant combinator, insert an implicit any-element `*`
tokens.slice( 0, i - 1 ).concat({ value: tokens[ i - 2 ].type === " " ? "*" : "" })
).replace( rtrim, "$1" ),
matcher,
i < j && matcherFromTokens( tokens.slice( i, j ) ),
j < len && matcherFromTokens( (tokens = tokens.slice( j )) ),
j < len && toSelector( tokens )
);
}
matchers.push( matcher );
}
}
return elementMatcher( matchers );
}
function matcherFromGroupMatchers( elementMatchers, setMatchers ) {
var bySet = setMatchers.length > 0,
byElement = elementMatchers.length > 0,
superMatcher = function( seed, context, xml, results, outermost ) {
var elem, j, matcher,
matchedCount = 0,
i = "0",
unmatched = seed && [],
setMatched = [],
contextBackup = outermostContext,
// We must always have either seed elements or outermost context
elems = seed || byElement && Expr.find["TAG"]( "*", outermost ),
// Use integer dirruns iff this is the outermost matcher
dirrunsUnique = (dirruns += contextBackup == null ? 1 : Math.random() || 0.1),
len = elems.length;
if ( outermost ) {
outermostContext = context === document || context || outermost;
}
// Add elements passing elementMatchers directly to results
// Support: IE<9, Safari
// Tolerate NodeList properties (IE: "length"; Safari: <number>) matching elements by id
for ( ; i !== len && (elem = elems[i]) != null; i++ ) {
if ( byElement && elem ) {
j = 0;
if ( !context && elem.ownerDocument !== document ) {
setDocument( elem );
xml = !documentIsHTML;
}
while ( (matcher = elementMatchers[j++]) ) {
if ( matcher( elem, context || document, xml) ) {
results.push( elem );
break;
}
}
if ( outermost ) {
dirruns = dirrunsUnique;
}
}
// Track unmatched elements for set filters
if ( bySet ) {
// They will have gone through all possible matchers
if ( (elem = !matcher && elem) ) {
matchedCount--;
}
// Lengthen the array for every element, matched or not
if ( seed ) {
unmatched.push( elem );
}
}
}
// `i` is now the count of elements visited above, and adding it to `matchedCount`
// makes the latter nonnegative.
matchedCount += i;
// Apply set filters to unmatched elements
// NOTE: This can be skipped if there are no unmatched elements (i.e., `matchedCount`
// equals `i`), unless we didn't visit _any_ elements in the above loop because we have
// no element matchers and no seed.
// Incrementing an initially-string "0" `i` allows `i` to remain a string only in that
// case, which will result in a "00" `matchedCount` that differs from `i` but is also
// numerically zero.
if ( bySet && i !== matchedCount ) {
j = 0;
while ( (matcher = setMatchers[j++]) ) {
matcher( unmatched, setMatched, context, xml );
}
if ( seed ) {
// Reintegrate element matches to eliminate the need for sorting
if ( matchedCount > 0 ) {
while ( i-- ) {
if ( !(unmatched[i] || setMatched[i]) ) {
setMatched[i] = pop.call( results );
}
}
}
// Discard index placeholder values to get only actual matches
setMatched = condense( setMatched );
}
// Add matches to results
push.apply( results, setMatched );
// Seedless set matches succeeding multiple successful matchers stipulate sorting
if ( outermost && !seed && setMatched.length > 0 &&
( matchedCount + setMatchers.length ) > 1 ) {
Sizzle.uniqueSort( results );
}
}
// Override manipulation of globals by nested matchers
if ( outermost ) {
dirruns = dirrunsUnique;
outermostContext = contextBackup;
}
return unmatched;
};
return bySet ?
markFunction( superMatcher ) :
superMatcher;
}
compile = Sizzle.compile = function( selector, match /* Internal Use Only */ ) {
var i,
setMatchers = [],
elementMatchers = [],
cached = compilerCache[ selector + " " ];
if ( !cached ) {
// Generate a function of recursive functions that can be used to check each element
if ( !match ) {
match = tokenize( selector );
}
i = match.length;
while ( i-- ) {
cached = matcherFromTokens( match[i] );
if ( cached[ expando ] ) {
setMatchers.push( cached );
} else {
elementMatchers.push( cached );
}
}
// Cache the compiled function
cached = compilerCache( selector, matcherFromGroupMatchers( elementMatchers, setMatchers ) );
// Save selector and tokenization
cached.selector = selector;
}
return cached;
};
/**
* A low-level selection function that works with Sizzle's compiled
* selector functions
* @param {String|Function} selector A selector or a pre-compiled
* selector function built with Sizzle.compile
* @param {Element} context
* @param {Array} [results]
* @param {Array} [seed] A set of elements to match against
*/
select = Sizzle.select = function( selector, context, results, seed ) {
var i, tokens, token, type, find,
compiled = typeof selector === "function" && selector,
match = !seed && tokenize( (selector = compiled.selector || selector) );
results = results || [];
// Try to minimize operations if there is only one selector in the list and no seed
// (the latter of which guarantees us context)
if ( match.length === 1 ) {
// Reduce context if the leading compound selector is an ID
tokens = match[0] = match[0].slice( 0 );
if ( tokens.length > 2 && (token = tokens[0]).type === "ID" &&
context.nodeType === 9 && documentIsHTML && Expr.relative[ tokens[1].type ] ) {
context = ( Expr.find["ID"]( token.matches[0].replace(runescape, funescape), context ) || [] )[0];
if ( !context ) {
return results;
// Precompiled matchers will still verify ancestry, so step up a level
} else if ( compiled ) {
context = context.parentNode;
}
selector = selector.slice( tokens.shift().value.length );
}
// Fetch a seed set for right-to-left matching
i = matchExpr["needsContext"].test( selector ) ? 0 : tokens.length;
while ( i-- ) {
token = tokens[i];
// Abort if we hit a combinator
if ( Expr.relative[ (type = token.type) ] ) {
break;
}
if ( (find = Expr.find[ type ]) ) {
// Search, expanding context for leading sibling combinators
if ( (seed = find(
token.matches[0].replace( runescape, funescape ),
rsibling.test( tokens[0].type ) && testContext( context.parentNode ) || context
)) ) {
// If seed is empty or no tokens remain, we can return early
tokens.splice( i, 1 );
selector = seed.length && toSelector( tokens );
if ( !selector ) {
push.apply( results, seed );
return results;
}
break;
}
}
}
}
// Compile and execute a filtering function if one is not provided
// Provide `match` to avoid retokenization if we modified the selector above
( compiled || compile( selector, match ) )(
seed,
context,
!documentIsHTML,
results,
!context || rsibling.test( selector ) && testContext( context.parentNode ) || context
);
return results;
};
// One-time assignments
// Sort stability
support.sortStable = expando.split("").sort( sortOrder ).join("") === expando;
// Support: Chrome 14-35+
// Always assume duplicates if they aren't passed to the comparison function
support.detectDuplicates = !!hasDuplicate;
// Initialize against the default document
setDocument();
// Support: Webkit<537.32 - Safari 6.0.3/Chrome 25 (fixed in Chrome 27)
// Detached nodes confoundingly follow *each other*
support.sortDetached = assert(function( el ) {
// Should return 1, but returns 4 (following)
return el.compareDocumentPosition( document.createElement("fieldset") ) & 1;
});
// Support: IE<8
// Prevent attribute/property "interpolation"
// https://msdn.microsoft.com/en-us/library/ms536429%28VS.85%29.aspx
if ( !assert(function( el ) {
el.innerHTML = "<a href='#'></a>";
return el.firstChild.getAttribute("href") === "#" ;
}) ) {
addHandle( "type|href|height|width", function( elem, name, isXML ) {
if ( !isXML ) {
return elem.getAttribute( name, name.toLowerCase() === "type" ? 1 : 2 );
}
});
}
// Support: IE<9
// Use defaultValue in place of getAttribute("value")
if ( !support.attributes || !assert(function( el ) {
el.innerHTML = "<input/>";
el.firstChild.setAttribute( "value", "" );
return el.firstChild.getAttribute( "value" ) === "";
}) ) {
addHandle( "value", function( elem, name, isXML ) {
if ( !isXML && elem.nodeName.toLowerCase() === "input" ) {
return elem.defaultValue;
}
});
}
// Support: IE<9
// Use getAttributeNode to fetch booleans when getAttribute lies
if ( !assert(function( el ) {
return el.getAttribute("disabled") == null;
}) ) {
addHandle( booleans, function( elem, name, isXML ) {
var val;
if ( !isXML ) {
return elem[ name ] === true ? name.toLowerCase() :
(val = elem.getAttributeNode( name )) && val.specified ?
val.value :
null;
}
});
}
return Sizzle;
})( window );
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