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*\/?>(?:<\/\1>|)$/,

    // 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