JQuery selector code (2) -- select method, jquery Selector

JQuery selector code (2) -- select method, jquery Selector

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/** The select method is one of the core methods of the Sizzle selector package. It mainly completes the following tasks: * 1. Call the tokenize method to parse the selector * 2. For a single block selector without an initial set (that is, the seed has no value assigned) (that is, there is no comma in the selector string ), * Do the following: * 1) if the first selector is ID and the context is document, directly obtain the object to replace the passed-in context object * 2) if the selector is a single selector, if it is of the id, class, or tag type, the corresponding DOM element is directly obtained and returned. * 3) obtain the matching DOM element of the last id, class, and tag type selector and assign it to the initial set (that is, the seed variable) * 4). Call the compile method to obtain and execute the pre-compiled code, get and return the matched DOM element ** @ param selector removes the leading and trailing blank selector string * @ param context to execute the initial context of the matching (that is, DOM Element Set ). If the context value is not assigned, the document is used. * @ Param results: the final result of the matched part. If results is not assigned a value, an empty array is assigned. * @ Param seed initial set */function select (selector, context, results, seed) {var I, tokens, token, type, find, // call the tokenize function to parse selectormatch = tokenize (selector); // if the initial set if (! Seed) {// Try to minimize operations if there is only one group // if there is only one group of selectors, that is, the selector string has no comma if (match. length = 1) {// Take a shortcut cut and set the context if the root selector // is an ID/** the following code is used to process the root selector as an ID shortcut ** use slice here [0] Create a new set, * Make sure that the original set will not be changed after the Code */tokens = match [0] = match [0]. slice (0);/** if the selector is of the id type and the second is a relational character (I .e., Or space). * The object to which the id belongs is used as the context to continue matching. ** the condition judgment here is: * tokens. length> 2: If tokens has more than two selectors * (token = tokens [0]). type = "ID": the type of the first selector is ID (starting with #), * support. getById: supports the getElementById function * context. nodeType = 9: the context object is document * documentIsHTML: the current processing is the HTML code * Expr. relative [tokens [1]. type]: The second tokens element is a link (I .e., + ~> Or space) * if all the preceding conditions are met, execute the statement body in if */if (tokens. length> 2 & (token = tokens [0]). type = "ID" & support. getById & context. nodeType === 9 & documentIsHTML & Expr. relative [tokens [1]. type]) {// point the current context to the Node object specified by the first ID selector context = (Expr. find ["ID"] (token. matches [0]. replace (runescape, funescape), context) | []) [0]; // if no ID object is specified in the current context, resultsif (! Context) {return results;} // remove the first ID selector = selector from the selector string. slice (tokens. shift (). value. length );} // Fetch a seed set for right-to-left matching/** the while LOOP below is used to obtain the initial set based on the last id, class, and tag type selector * for Example simple Example: if the selector is "div [title = '2']", * the code obtains all div nodes under the context based on the div and assigns this set to the seed variable, * Then, call the compile function to generate the pre-compiled code. * The pre-compiled code completes the matching of [title = '2'] in the above initial set. ** first, check whether the selector string contains any character that matches the needsContext Regular Expression * if no character exists, the selector filters D from right to left. OM node * Otherwise, run the program into pre-compiled code (call the compile method ). * // ** "NeedsContext": new RegExp ("^" + whitespace * + "* [> + ~] | :( Even | odd | eq | gt | lt | nth | first | last )(?: \ ("* + Whitespace + "*((? :-\ D )? \ D *) "+ whitespace * +" * \) | )(? = [^-] | $) "," I ") * needsContext is used to match whether the selector string contains the following content: * 1.> + ~ Three Relational operators * 2,: even,: odd,: eq,: gt,: lt,: nth,: first,: last, eight pseudo Classes ,(? = [^-] | $) Is used to filter out objects similar: other selector with a first-child or a middle bar that starts with the preceding eight words */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/** rsibling = new RegExp (whitespace + "* [++] ") * Rsibling is used to determine whether the token selector is a sibling character */if (seed = find (token. matches [0]. replace (runescape, funescape), rsibling. test (tokens [0]. type) & context. parentNode | context) {// If seed is empty or no tokens remain, we can // return early // remove the recently used selector tokens. splice (I, 1); selector = seed. length & toSelector (tokens);/** if selector is empty, the selector is only of the single id, class, and tag type. * The obtained result is returned directly. Otherwise, continue matching */if (! Selector) {push. apply (results, seed); return results;} break ;}}}}} // Compile and execute a filtering function // Provide 'match' to avoid retokenization if we modified the // selector above/** first execute compile (selector, match ), it returns a pre-compiled function, * and then calls this function to obtain the final matching result */compile (selector, match) (seed, context ,! DocumentIsHTML, results, rsibling. test (selector); return results ;}

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JQuery selector code (1) -- Sizzle Method

JQuery selector code (2) -- select Method

JQuery selector code (3) -- tokenize Method