jquery1.7.2的源码分析（一）

说到jquery可能是大家最经常用到的,在日常的编写程序中最经常使用到，在使用jquery插件的同时，深入的解读jquery源码有利于我们学到设计的思想和实现的技巧

在jquery源码的分析中，其中艾伦 Aaron的博客有深入的介绍，其在慕课网上也有相应的源码的解读，感兴趣的同学可以去看看

此博客是鉴于自己对jquery的学习中的所记录的，学习的jquery源码

jquery源码整体分析

//采用闭包传入window
(function( window, undefined ) {//doing something})(window)

 var document = window.document,
navigator = window.navigator,
location = window.location;
var jQuery = (function() {
// Define a local copy of jQuery
//构造函数
var jQuery = function( selector, context ) {
// The jQuery object is actually just the init constructor 'enhanced'
//注意这是是new 一个 init
return new jQuery.fn.init( selector, context, rootjQuery );
},
// Map over jQuery in case of overwrite
_jQuery = window.jQuery,
// Map over the $ in case of overwrite
_$ = window.$,
// A central reference to the root jQuery(document)
rootjQuery,
// A simple way to check for HTML strings or ID strings
// Prioritize #id over tag to avoid XSS via location.hash (#9521)
quickExpr = /^(?:[^#<]*(<[\w\W]+>)[^>]*$|#([\w\-]*)$)/,
// Check if a string has a non-whitespace character in it
//不为空白符
rnotwhite = /\S/,
//匹配首字母以空白符开始的
// 匹配末尾以空白符结束的
trimLeft = /^\s+/,
trimRight = /\s+$/,
//匹配一个独立的标签如div
如，
rsingleTag = /^<(\w+)\s*\/?>(?:<\/\1>)?$/,
// JSON RegExp
rvalidchars = /^[\],:{}\s]*$/,
rvalidescape = /\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g,
rvalidtokens = /"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g,
rvalidbraces = /(?:^|:|,)(?:\s*\[)+/g,
// Useragent RegExp浏览器的正则表达式
rwebkit = /(webkit)[ \/]([\w.]+)/,
ropera = /(opera)(?:.*version)?[ \/]([\w.]+)/,
rmsie = /(msie) ([\w.]+)/,
rmozilla = /(mozilla)(?:.*? rv:([\w.]+))?/,
// Matches dashed string for camelizing
rdashAlpha = /-([a-z]|[0-9])/ig,
rmsPrefix = /^-ms-/,
//驼峰式
fcamelCase = function( all, letter ) {
return ( letter + "" ).toUpperCase();
},
// Keep a UserAgent string for use with jQuery.browser
userAgent = navigator.userAgent,
// For matching the engine and version of the browser
browserMatch,
// The deferred used on DOM ready
readyList,
// The ready event handler
DOMContentLoaded,
// Save a reference to some core methods
toString = Object.prototype.toString,
hasOwn = Object.prototype.hasOwnProperty,
push = Array.prototype.push,
slice = Array.prototype.slice,
trim = String.prototype.trim,
indexOf = Array.prototype.indexOf,
// [[Class]] -> type pairs
class2type = {};
jQuery.fn = jQuery.prototype = {
constructor: jQuery,
init: function( selector, context, rootjQuery ) {
var match, elem, ret, doc;
// Handle $(""), $(null), or $(undefined)
if ( !selector ) {
return this;
}
// Handle $(DOMElement)
if ( selector.nodeType ) {
//先保持疑问
this.context = this[0] = selector;
this.length = 1;
return this;
}
// The body element only exists once, optimize finding it
if ( selector === "body" && !context && document.body ) {
this.context = document;
this[0] = document.body;
this.selector = selector;
this.length = 1;
return this;
}
// Handle HTML strings
if ( typeof selector === "string" ) {
// Are we dealing with HTML string or an ID?
if ( selector.charAt(0) === "<" && selector.charAt( selector.length - 1 ) === ">" && selector.length >= 3 ) {
// Assume that strings that start and end with <> are HTML and skip the regex check
match = [ null, selector, null ];
} else {
match = quickExpr.exec( selector );
}
// Verify a match, and that no context was specified for #id
if ( match && (match[1] || !context) ) {
// HANDLE: $(html) -> $(array)
if ( match[1] ) {
context = context instanceof jQuery ? context[0] : context;
doc = ( context ? context.ownerDocument || context : document );
// If a single string is passed in and it's a single tag
// just do a createElement and skip the rest
ret = rsingleTag.exec( selector );
if ( ret ) {
if ( jQuery.isPlainObject( context ) ) {
selector = [ document.createElement( ret[1] ) ];
jQuery.fn.attr.call( selector, context, true );
} else {
selector = [ doc.createElement( ret[1] ) ];
}
} else {
ret = jQuery.buildFragment( [ match[1] ], [ doc ] );
selector = ( ret.cacheable ? jQuery.clone(ret.fragment) : ret.fragment ).childNodes;
}
return jQuery.merge( this, selector );
// HANDLE: $("#id")
} else {
elem = document.getElementById( match[2] );
// Check parentNode to catch when Blackberry 4.6 returns
// nodes that are no longer in the document #6963
if ( elem && elem.parentNode ) {
// Handle the case where IE and Opera return items
// by name instead of ID
if ( elem.id !== match[2] ) {
return rootjQuery.find( selector );
}
// Otherwise, we inject the element directly into the jQuery object
this.length = 1;
this[0] = elem;
}
this.context = document;
this.selector = selector;
return this;
}
// HANDLE: $(expr, $(...))
} else if ( !context || context.jquery ) {
return ( context || rootjQuery ).find( selector );
// HANDLE: $(expr, context)
// (which is just equivalent to: $(context).find(expr)
} else {
return this.constructor( context ).find( selector );
}
// HANDLE: $(function)
// Shortcut for document ready
} else if ( jQuery.isFunction( selector ) ) {
return rootjQuery.ready( selector );
}
if ( selector.selector !== undefined ) {
this.selector = selector.selector;
this.context = selector.context;
}
return jQuery.makeArray( selector, this );
},
// Start with an empty selector
selector: "",
// The current version of jQuery being used
jquery: "1.7.2",
// The default length of a jQuery object is 0
length: 0,
// The number of elements contained in the matched element set
size: function() {
//元素的个数
return this.length;
},
toArray: function() {
//可以将jquery对象转化为dom对象
return slice.call( this, 0 );
},
// Get the Nth element in the matched element set OR
// Get the whole matched element set as a clean array
get: function( num ) {
return num == null ?
// Return a 'clean' array
//
this.toArray() :
// Return just the object
//例如：$('div').get(0)取到一个div
( num < 0 ? this[ this.length + num ] : this[ num ] );
},
// Take an array of elements and push it onto the stack
// (returning the new matched element set)
pushStack: function( elems, name, selector ) {
// Build a new jQuery matched element set
var ret = this.constructor();
if ( jQuery.isArray( elems ) ) {
push.apply( ret, elems );
} else {
jQuery.merge( ret, elems );
}
// Add the old object onto the stack (as a reference)
ret.prevObject = this;
ret.context = this.context;
//eg.div.slice(0,2)
//console.log：[div, div, prevObject: init[3], context: document, selector: "div.slice(0,2)"]
if ( name === "find" ) {
ret.selector = this.selector + ( this.selector ? " " : "" ) + selector;
} else if ( name ) {
ret.selector = this.selector + "." + name + "(" + selector + ")";
}
return ret;
},
// Execute a callback for every element in the matched set.
// (You can seed the arguments with an array of args, but this is
// only used internally.)
each: function( callback, args ) {
return jQuery.each( this, callback, args );
},
ready: function( fn ) {
// Attach the listeners
jQuery.bindReady();
// Add the callback
readyList.add( fn );
return this;
},
eq: function( i ) {
i = +i;
return i === -1 ?
this.slice( i ) :
this.slice( i, i + 1 );
},
first: function() {
return this.eq( 0 );
},
last: function() {
return this.eq( -1 );
},
slice: function() {
return this.pushStack( slice.apply( this, arguments ),
"slice", slice.call(arguments).join(",") );
},
map: function( callback ) {
return this.pushStack( jQuery.map(this, function( elem, i ) {
return callback.call( elem, i, elem );
}));
},
end: function() {
return this.prevObject || this.constructor(null);
},
// For internal use only.
// Behaves like an Array's method, not like a jQuery method.
push: push,
sort: [].sort,
splice: [].splice
};
// Give the init function the jQuery prototype for later instantiation
jQuery.fn.init.prototype = jQuery.fn;