深入学习jquery源码之filter()与find()
filter(expr|obj|ele|fn)
概述
筛选出与指定表达式匹配的元素集合。
这个方法用于缩小匹配的范围。用逗号分隔多个表达式
参数
expr String
字符串值，包含供匹配当前元素集合的选择器表达式。
jQuery object object
现有的jQuery对象，以匹配当前的元素。
element Expression
一个用于匹配元素的DOM元素。
function(index) Function
一个函数用来作为测试元素的集合。它接受一个参数index，这是元素在jQuery集合的索引。在函数， this指的是当前的DOM元素。
保留带有select类的元素
<p>Hello</p><p>Hello Again</p><p class="selected">And Again</p>
$("p").filter(".selected")[ <p class="selected">And Again</p> ]
保留第一个以及带有select类的元素
<p>Hello</p><p>Hello Again</p><p class="selected">And Again</p>
$("p").filter(".selected, :first")[ <p>Hello</p>, <p class="selected">And Again</p> ]
保留子元素中不含有ol的元素。
<p><ol><li>Hello</li></ol></p><p>How are you?</p>
$("p").filter(function(index) {
return $("ol", this).length == 0;
});[ <p>How are you?</p> ]
find(expr|obj|ele)
概述
搜索所有与指定表达式匹配的元素。这个函数是找出正在处理的元素的后代元素的好方法。
所有搜索都依靠jQuery表达式来完成。这个表达式可以使用CSS1-3的选择器语法来写。
参数
expr String
用于查找的表达式
jQuery object object
一个用于匹配元素的jQuery对象
element DOMElement
一个DOM元素
从所有的段落开始，进一步搜索下面的span元素。与$("p span")相同。
<p><span>Hello</span>, how are you?</p>
$("p").find("span")[ <span>Hello</span> ]
jquery源码
jQuery.find = Sizzle;
jQuery.expr = Sizzle.selectors;
jQuery.expr[":"] = jQuery.expr.pseudos;
jQuery.unique = Sizzle.uniqueSort;
jQuery.text = Sizzle.getText;
jQuery.isXMLDoc = Sizzle.isXML;
jQuery.contains = Sizzle.contains;
var Sizzle =
(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(),
sortOrder = function (a, b) {
if (a === b) {
hasDuplicate = true;
}
return 0;
},
// General-purpose constants
MAX_NEGATIVE = 1 << 31,
// 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
// http://jsperf.com/thor-indexof-vs-for/5
indexOf = function (list, elem) {
var i = 0,
len = list.length;
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
// Whitespace characters http://www.w3.org/TR/css3-selectors/#whitespace
whitespace = "[\\x20\\t\\r\\n\\f]",
// http://www.w3.org/TR/css3-syntax/#characters
characterEncoding = "(?:\\\\.|[\\w-]|[^\\x00-\\xa0])+",
// Loosely modeled on CSS identifier characters
// An unquoted value should be a CSS identifier http://www.w3.org/TR/css3-selectors/#attribute-selectors
// Proper syntax: http://www.w3.org/TR/CSS21/syndata.html#value-def-identifier
identifier = characterEncoding.replace("w", "w#"),
// Attribute selectors: http://www.w3.org/TR/selectors/#attribute-selectors
attributes = "\\[" + whitespace + "*(" + characterEncoding + ")(?:" + whitespace +
// Operator (capture 2)
"*([*^$|!~]?=)" + whitespace +
// "Attribute values must be CSS identifiers [capture 5] or strings [capture 3 or capture 4]"
"*(?:'((?:\\\\.|[^\\\\'])*)'|\"((?:\\\\.|[^\\\\\"])*)\"|(" + identifier + "))|)" + whitespace +
"*\\]",
pseudos = ":(" + characterEncoding + ")(?:\\((" +
// 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 + "+$", "g"),
rcomma = new RegExp("^" + whitespace + "*," + whitespace + "*"),
rcombinators = new RegExp("^" + whitespace + "*([>+~]|" + whitespace + ")" + whitespace + "*"),
rattributeQuotes = new RegExp("=" + whitespace + "*([^\\]'\"]*?)" + whitespace + "*\\]", "g"),
rpseudo = new RegExp(pseudos),
ridentifier = new RegExp("^" + identifier + "$"),
matchExpr = {
"ID": new RegExp("^#(" + characterEncoding + ")"),
"CLASS": new RegExp("^\\.(" + characterEncoding + ")"),
"TAG": new RegExp("^(" + characterEncoding.replace("w", "w*") + ")"),
"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")
},
rinputs = /^(?:input|select|textarea|button)$/i,
rheader = /^h\d$/i,
rnative = /^[^{]+\{\s*\[native \w/,
// Easily-parseable/retrievable ID or TAG or CLASS selectors
rquickExpr = /^(?:#([\w-]+)|(\w+)|\.([\w-]+))$/,
rsibling = /[+~]/,
rescape = /'|\\/g,
// CSS escapes http://www.w3.org/TR/CSS21/syndata.html#escaped-characters
runescape = new RegExp("\\\\([\\da-f]{1,6}" + whitespace + "?|(" + whitespace + ")|.)", "ig"),
funescape = function (_, escaped, escapedWhitespace) {
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);
},
// Used for iframes
// See setDocument()
// Removing the function wrapper causes a "Permission Denied"
// error in IE
unloadHandler = function () {
setDocument();
};
// Optimize for push.apply( _, NodeList )
try {
push.apply(
(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
while ((target[j++] = els[i++])) { }
target.length = j - 1;
}
};
}
function Sizzle(selector, context, results, seed) {
var match, elem, m, nodeType,
// QSA vars
i, groups, old, nid, newContext, newSelector;
if ((context ? context.ownerDocument || context : preferredDoc) !== document) {
setDocument(context);
}
context = context || document;
results = results || [];
nodeType = context.nodeType;
if (typeof selector !== "string" || !selector ||
nodeType !== 1 && nodeType !== 9 && nodeType !== 11) {
return results;
}
if (!seed && documentIsHTML) {
// Try to shortcut find operations when possible (e.g., not under DocumentFragment)
if (nodeType !== 11 && (match = rquickExpr.exec(selector))) {
// Speed-up: Sizzle("#ID")
if ((m = match[1])) {
if (nodeType === 9) {
elem = context.getElementById(m);
// Check parentNode to catch when Blackberry 4.6 returns
// nodes that are no longer in the document (jQuery #6963)
if (elem && elem.parentNode) {
// Handle the case where IE, Opera, and Webkit return items
// by name instead of ID
if (elem.id === m) {
results.push(elem);
return results;
}
} else {
return results;
}
} else {
// Context is not a document
if (context.ownerDocument && (elem = context.ownerDocument.getElementById(m)) &&
contains(context, elem) && elem.id === m) {
results.push(elem);
return results;
}
}
// Speed-up: Sizzle("TAG")
} else if (match[2]) {
push.apply(results, context.getElementsByTagName(selector));
return results;
// Speed-up: Sizzle(".CLASS")
} else if ((m = match[3]) && support.getElementsByClassName) {
push.apply(results, context.getElementsByClassName(m));
return results;
}
}
// QSA path
if (support.qsa && (!rbuggyQSA || !rbuggyQSA.test(selector))) {
nid = old = expando;
newContext = context;
newSelector = nodeType !== 1 && selector;
// qSA works strangely on Element-rooted queries
// We can work around this by specifying an extra ID on the root
// and working up from there (Thanks to Andrew Dupont for the technique)
// IE 8 doesn't work on object elements
if (nodeType === 1 && context.nodeName.toLowerCase() !== "object") {
groups = tokenize(selector);
if ((old = context.getAttribute("id"))) {
nid = old.replace(rescape, "\\$&");
} else {
context.setAttribute("id", nid);
}
nid = "[id='" + nid + "'] ";
i = groups.length;
while (i--) {
groups[i] = nid + toSelector(groups[i]);
}
newContext = rsibling.test(selector) && testContext(context.parentNode) || context;
newSelector = groups.join(",");
}
if (newSelector) {
try {
push.apply(results,
newContext.querySelectorAll(newSelector)
);
return results;
} catch (qsaError) {
} finally {
if (!old) {
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() {
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;
}
Sizzle.matches = function (expr, elements) {
return Sizzle(expr, null, null, elements);
};
Sizzle.matchesSelector = function (elem, expr) {
// Set document vars if needed
if ((elem.ownerDocument || elem) !== document) {
setDocument(elem);
}
// Make sure that attribute selectors are quoted
expr = expr.replace(rattributeQuotes, "='$1']");
if (support.matchesSelector && documentIsHTML &&
(!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) { }
}
return Sizzle(expr, document, null, [elem]).length > 0;
};
return Sizzle;
})(window);
var risSimple = /^.[^:#\[\.,]*$/;
// Implement the identical functionality for filter and not
function winnow(elements, qualifier, not) {
if (jQuery.isFunction(qualifier)) {
return jQuery.grep(elements, function (elem, i) {
/* jshint -W018 */
return !!qualifier.call(elem, i, elem) !== not;
});
}
if (qualifier.nodeType) {
return jQuery.grep(elements, function (elem) {
return (elem === qualifier) !== not;
});
}
if (typeof qualifier === "string") {
if (risSimple.test(qualifier)) {
return jQuery.filter(qualifier, elements, not);
}
qualifier = jQuery.filter(qualifier, elements);
}
return jQuery.grep(elements, function (elem) {
return (jQuery.inArray(elem, qualifier) >= 0) !== not;
});
}
jQuery.filter = function (expr, elems, not) {
var elem = elems[0];
if (not) {
expr = ":not(" + expr + ")";
}
return elems.length === 1 && elem.nodeType === 1 ?
jQuery.find.matchesSelector(elem, expr) ? [elem] : [] :
jQuery.find.matches(expr, jQuery.grep(elems, function (elem) {
return elem.nodeType === 1;
}));
};
jQuery.fn = jQuery.prototype = {
// The current version of jQuery being used
jquery: version,
constructor: jQuery,
// Start with an empty selector
selector: "",
// The default length of a jQuery object is 0
length: 0,
toArray: function () {
return slice.call(this);
},
// Take an array of elements and push it onto the stack
// (returning the new matched element set)
pushStack: function (elems) {
// Build a new jQuery matched element set
var ret = jQuery.merge(this.constructor(), elems);
// Add the old object onto the stack (as a reference)
ret.prevObject = this;
ret.context = this.context;
// Return the newly-formed element set
return ret;
}
// For internal use only.
// Behaves like an Array's method, not like a jQuery method.
push: push,
sort: deletedIds.sort,
splice: deletedIds.splice
};
jQuery.fn.extend({
find: function (selector) {
var i,
ret = [],
self = this,
len = self.length;
if (typeof selector !== "string") {
return this.pushStack(jQuery(selector).filter(function () {
for (i = 0; i < len; i++) {
if (jQuery.contains(self[i], this)) {
return true;
}
}
}));
}
for (i = 0; i < len; i++) {
jQuery.find(selector, self[i], ret);
}
// Needed because $( selector, context ) becomes $( context ).find( selector )
ret = this.pushStack(len > 1 ? jQuery.unique(ret) : ret);
ret.selector = this.selector ? this.selector + " " + selector : selector;
return ret;
},
filter: function (selector) {
return this.pushStack(winnow(this, selector || [], false));
}
});
标签：jquery,jQuery,return,whitespace,function,elem,filter,源码,context From： https://blog.51cto.com/u_11837698/6081940