jquery源码学习（二）——jquery中的变量

jquery在 21-93 行提供了变量

 1 var
 2     // A central reference to the root jQuery(document)
 3     rootjQuery,
 4 
 5     // The deferred used on DOM ready
 6     readyList,
 7 
 8     // Support: IE9
 9     // For `typeof xmlNode.method` instead of `xmlNode.method !== undefined`
10     core_strundefined = typeof undefined,
11 
12     // Use the correct document accordingly with window argument (sandbox)
13     location = window.location,
14     document = window.document,
15     docElem = document.documentElement,
16 
17     // Map over jQuery in case of overwrite
18     _jQuery = window.jQuery,
19 
20     // Map over the $ in case of overwrite
21     _$ = window.$,
22 
23     // [[Class]] -> type pairs
24     class2type = {},
25 
26     // List of deleted data cache ids, so we can reuse them
27     core_deletedIds = [],
28 
29     core_version = "2.0.3",
30 
31     // Save a reference to some core methods
32     core_concat = core_deletedIds.concat,
33     core_push = core_deletedIds.push,
34     core_slice = core_deletedIds.slice,
35     core_indexOf = core_deletedIds.indexOf,
36     core_toString = class2type.toString,
37     core_hasOwn = class2type.hasOwnProperty,
38     core_trim = core_version.trim,
39 
40     // Define a local copy of jQuery
41     jQuery = function( selector, context ) {
42         // The jQuery object is actually just the init constructor 'enhanced'
43         return new jQuery.fn.init( selector, context, rootjQuery );
44     },
45 
46     // Used for matching numbers
47     core_pnum = /[+-]?(?:d*.|)d+(?:[eE][+-]?d+|)/.source,
48 
49     // Used for splitting on whitespace
50     core_rnotwhite = /S+/g,
51 
52     // A simple way to check for HTML strings
53     // Prioritize #id over <tag> to avoid XSS via location.hash (#9521)
54     // Strict HTML recognition (#11290: must start with <)
55     rquickExpr = /^(?:s*(<[wW]+>)[^>]*|#([w-]*))$/,
56 
57     // Match a standalone tag
58     rsingleTag = /^<(w+)s*/?>(?:</1>|)$/,
59 
60     // Matches dashed string for camelizing
61     rmsPrefix = /^-ms-/,
62     rdashAlpha = /-([da-z])/gi,
63 
64     // Used by jQuery.camelCase as callback to replace()
65     fcamelCase = function( all, letter ) {
66         return letter.toUpperCase();
67     },
68 
69     // The ready event handler and self cleanup method
70     completed = function() {
71         document.removeEventListener( "DOMContentLoaded", completed, false );
72         window.removeEventListener( "load", completed, false );
73         jQuery.ready();
74     };

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