var rnotwhite = (/\S+/g);//匹配空格，返回数组// String to Object options format cache
var optionsCache = {};// Convert String-formatted options into Object-formatted ones and store in cache
function createOptions( options ) {var object = optionsCache[ options ] = {};jQuery.each( options.match( rnotwhite ) || [], function( _, flag ) {//接受的字符串的组合传参数，可以使用空格分割object[ flag ] = true;});return object;
}/** Create a callback list using the following parameters:* By default a callback list will act like an event callback list and can be* "fired" multiple times.** Possible options://这里提供四个可选参数once、memory、unique、stopOnFalse 对函数队列进行特殊控制。*/
jQuery.Callbacks = function( options ) {// Convert options from String-formatted to Object-formatted if needed// (we check in cache first)options = typeof options === "string" ?( optionsCache[ options ] || createOptions( options ) ) :jQuery.extend( {}, options );var // Flag to know if list is currently firing
        firing,// Last fire value (for non-forgettable lists)
        memory,// Flag to know if list was already fired
        fired,// End of the loop when firing
        firingLength,// Index of currently firing callback (modified by remove if needed)
        firingIndex,// First callback to fire (used internally by add and fireWith)
        firingStart,// Actual callback listlist = [],// Stack of fire calls for repeatable listsstack = !options.once && [],//传递once参数后，则回调执行完毕之后，list会被清空([])或置为undefined// Fire callbacksfire = function( data ) {//闭包方法memory = options.memory && data;fired = true;//用来判断回调队列是否被执行过一次firingIndex = firingStart || 0;//上次fire的位置，用作设置memory时，add之后直接触发回调。firingStart = 0;firingLength = list.length;firing = true;for ( ; list && firingIndex < firingLength; firingIndex++ ) {if ( list[ firingIndex ].apply( data[ 0 ], data[ 1 ] ) === false && options.stopOnFalse ) {//判断是否需要判读回调返回值memory = false; // To prevent further calls using add---//强制修改memorybreak;}}firing = false;if ( list ) {if ( stack ) {//是否为false，初始化时是通过是否传递once来控制，if ( stack.length ) {fire( stack.shift() );}} else if ( memory ) {//这里清空目的在于，add之后直接fire新添加的回调。list = [];} else {self.disable();}}},// Actual Callbacks objectself = {// Add a callback or a collection of callbacks to the listadd: function() {if ( list ) {// First, we save the current lengthvar start = list.length;(function add( args ) {//添加回调list集合jQuery.each( args, function( _, arg ) {var type = jQuery.type( arg );if ( type === "function" ) {if ( !options.unique || !self.has( arg ) ) {list.push( arg );}} else if ( arg && arg.length && type !== "string" ) {// Inspect recursively
                                add( arg );}});})( arguments );// Do we need to add the callbacks to the// current firing batch?if ( firing ) {firingLength = list.length;// With memory, if we're not firing then// we should call right away} else if ( memory ) {//这里如果option.memory有值的话，memory已经被修改为[context,arguments]firingStart = start;fire( memory );}}return this;},// Remove a callback from the listremove: function() {//从回调队列中 删除函数。if ( list ) {jQuery.each( arguments, function( _, arg ) {var index;while ( ( index = jQuery.inArray( arg, list, index ) ) > -1 ) {list.splice( index, 1 );// Handle firing indexesif ( firing ) {if ( index <= firingLength ) {firingLength--;}if ( index <= firingIndex ) {firingIndex--;}}}});}return this;},// Check if a given callback is in the list.// If no argument is given, return whether or not list has callbacks attached.has: function( fn ) {return fn ? jQuery.inArray( fn, list ) > -1 : !!( list && list.length );},// Remove all callbacks from the listempty: function() {//清空回调队列list = [];firingLength = 0;return this;},// Have the list do nothing anymoredisable: function() {//整个回调队列失效list = stack = memory = undefined;return this;},// Is it disabled?disabled: function() {return !list;},// Lock the list in its current statelock: function() {//在当前状态下锁死stack = undefined;if ( !memory ) {self.disable();}return this;},// Is it locked?locked: function() {return !stack;},// Call all callbacks with the given context and argumentsfireWith: function( context, args ) {if ( list && ( !fired || stack ) ) {args = args || [];args = [ context, args.slice ? args.slice() : args ];if ( firing ) {stack.push( args );} else {fire( args );//若$.Callback调用时设置memory，则会闭包中memory被修改为此时的args<==>[context,args]}}return this;},// Call all the callbacks with the given argumentsfire: function() {//切换执行上下问self.fireWith( this, arguments );return this;},// To know if the callbacks have already been called at least oncefired: function() {//判断回调队列已经被触发过一次return !!fired;}};return self;
};