JQuery 1.10.2 源码分析学习1

前面转了一篇讲JQuery总体框架的文章，建议先阅读，可以让大家对JQuery有一个整体的了解。闲话不多说先上源码：

var
	// The deferred used on DOM ready
	readyList,

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

	// Support: IE<10
	// 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 = "1.10.2",

	// 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,

	// Make sure we trim BOM and NBSP (here's looking at you, Safari 5.0 and IE)
	rtrim = /^[\s\uFEFF\xA0]+|[\s\uFEFF\xA0]+$/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>|)$/,

	// JSON RegExp
	rvalidchars = /^[\],:{}\s]*$/,
	rvalidbraces = /(?:^|:|,)(?:\s*\[)+/g,
	rvalidescape = /\\(?:["\\\/bfnrt]|u[\da-fA-F]{4})/g,
	rvalidtokens = /"[^"\\\r\n]*"|true|false|null|-?(?:\d+\.|)\d+(?:[eE][+-]?\d+|)/g,

	// 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
	completed = function( event ) {

		// readyState === "complete" is good enough for us to call the dom ready in oldIE
		if ( document.addEventListener || event.type === "load" || document.readyState === "complete" ) {
			detach();
			jQuery.ready();
		}
	},
	// Clean-up method for dom ready events
	detach = function() {
		if ( document.addEventListener ) {
			document.removeEventListener( "DOMContentLoaded", completed, false );
			window.removeEventListener( "load", completed, false );

		} else {
			document.detachEvent( "onreadystatechange", completed );
			window.detachEvent( "onload", completed );
		}
	};

以上定义了一些函数变量和方法。（这样解释不知道对不对？）

并且JQuery是在一个匿名函数中，用了var就避免了全局变量的使用，这样的好处就是不会和其他库或者插件冲突。但是JQuery还是有一个全局变量的那就是$。

// 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 );
},

上面这段代码作用是构建JQuery的对象。实际上我们用$()返回的是JQuery.fn.init对象的实例，根据JS的语法我们可以看出，这个对象的prototype指向了JQuery的prototype，这样实现了链式编程的操作。

function( window, undefined )，undefined参数传进来的好处就是避免了undefined变量被污染。