jquery源码学习（二）——jquery中的变量

jquery在 21-93 行提供了变量

　　

 var
     // A central reference to the root jQuery(document)
     rootjQuery,

     // The deferred used on DOM ready
     readyList,

     // Support: IE9
     // For `typeof xmlNode.method` instead of `xmlNode.method !== undefined`
     core_strundefined = typeof undefined,

     // Use the correct document accordingly with window argument (sandbox)
     location = window.location,
     document = window.document,
     docElem = document.documentElement,

     // Map over jQuery in case of overwrite
     _jQuery = window.jQuery,

     // Map over the $ in case of overwrite
     _$ = window.$,

     // [[Class]] -> type pairs
     class2type = {},

     // List of deleted data cache ids, so we can reuse them
     core_deletedIds = [],

     core_version = "2.0.3",

     // Save a reference to some core methods
     core_concat = core_deletedIds.concat,
     core_push = core_deletedIds.push,
     core_slice = core_deletedIds.slice,
     core_indexOf = core_deletedIds.indexOf,
     core_toString = class2type.toString,
     core_hasOwn = class2type.hasOwnProperty,
     core_trim = core_version.trim,

     // Define a local copy of jQuery
     jQuery = function( selector, context ) {
         // The jQuery object is actually just the init constructor 'enhanced'
         return new jQuery.fn.init( selector, context, rootjQuery );
     },

     // Used for matching numbers
     core_pnum = /[+-]?(?:\d*\.|)\d+(?:[eE][+-]?\d+|)/.source,

     // Used for splitting on whitespace
     core_rnotwhite = /\S+/g,

     // A simple way to check for HTML strings
     // Prioritize #id over <tag> to avoid XSS via location.hash (#9521)
     // Strict HTML recognition (#11290: must start with <)
     rquickExpr = /^(?:\s*(<[\w\W]+>)[^>]*|#([\w-]*))$/,

     // Match a standalone tag
     rsingleTag = /^<(\w+)\s*\/?>(?:<\/\>|)$/,

     // Matches dashed string for camelizing
     rmsPrefix = /^-ms-/,
     rdashAlpha = /-([\da-z])/gi,

     // Used by jQuery.camelCase as callback to replace()
     fcamelCase = function( all, letter ) {
         return letter.toUpperCase();
     },

     // The ready event handler and self cleanup method
     completed = function() {
         document.removeEventListener( "DOMContentLoaded", completed, false );
         window.removeEventListener( "load", completed, false );
         jQuery.ready();
     };

一次性声明逗号隔开 

rootJQuery 

//25行中的  rootJQuery  在 866 行 = jQuery(document)

//A central reference to the root jQuery(document) 意思这是jquery最核心的概念，jQuery(document) 就是把选择到的东西保存起来。

//保存起来的原因，首先原因    1. 便于压缩  2. 语义化  3. 可维护

readyList

//和Dom加载相关的对象数组；在集合中保存中要操作的DOM元素。

// The deferred used on DOM ready

core_strundefined

//字符串类型的undefined，typeof window.a == "undefined" 这种判断方法的兼容性更好。

location documentElem document

//字符串类型的undefined，typeof window.a == "undefined" 这种判断方法的兼容性更好。

// Use the correct document accordingly with window argument (sandbox)
location = window.location,
document = window.document,
docElem = document.documentElement,

_Jquery 和 _$ 

//为了防止命名冲突，把以前的jquery和$保存起来到_jquery和_$， 如果没有命名冲突，那么他们就是undefined

core_deletedId 和 core_version 

//这两个是和数据缓存有关系的数据，包括下边的core_开头的其他数据，在此不作解释

jQuery

//返回一个初始化的 jquery 对象

//return new jQuery.fn.init( selector, context, rootjQuery );

//jQuery.fn = jQuery.prototype

//jQuery.fn.init.prototype = jQuery.prototype ;

//所以其实jquery.fn.init其实返回一个jquery对象 , jquery.fn.int和jquery是一样的。

正则匹配

//core_pnum : 匹配各种数字

//rquickExpr : 匹配标签样式

//rsingleTag : 匹配单标签样式

//rmsPeofixed : 匹配ie样式

completed 和 fcamelCase

//前者在 DOM 加载完成后的ready();

//后者返回大写