<script>
$().ready(function() {
var optionsCache = {};
var core_rnotwhite = /\S+/g;
function createOptions( options ) {
var object = optionsCache[ options ] = {};
jQuery.each( options.match( core_rnotwhite ) || [], function( _, flag ) {
object[ flag ] = true;
});
return object;
}
jQuery.Callbacks = function( options, ly ) {
// 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 );//jQuery.extend( {}, options ) ==> 如果没有传递参数进来,或者options不是字符串的情况,如果options是对象,则options = options
//jQuery.extend( {}, options ) ==>如果options是[],则options为{0: options}
var // Last fire value (for non-forgettable lists)
memory,
// Flag to know if list was already fired
fired,
// Flag to know if list is currently firing
firing,
// First callback to fire (used internally by add and fireWith)
firingStart,
// End of the loop when firing
firingLength,
// Index of currently firing callback (modified by remove if needed)
firingIndex,
// Actual callback list
list = [],
// Stack of fire calls for repeatable lists
stack = !options.once && [],//这种情况是对象参数有传once
// Fire callbacks
fire = function( data ) {
memory = options.memory && data;
fired = true;//表示当前函数已经触发过一次了
firingIndex = firingStart || 0;
firingStart = 0;
firingLength = list.length;
firing = true;//正在触发当中
for ( ; list && firingIndex < firingLength; firingIndex++ ) {
if ( list[ firingIndex ].apply( data[ 0 ], data[ 1 ] ) === false && options.stopOnFalse ) {
/*
*list[ firingIndex ].apply( data[ 0 ], data[ 1 ] )-->对数组下面的每一个项进行操作,
*data[0]-->执行环境,data[1],是指Callbacks对象触发fire()时传递进来的参数
*list[ firingIndex ].apply( data[ 0 ], data[ 1 ] ) === false表示,回调函数返回为false的时候
*list = [aaa, bbb]-->list[ 0 ].apply( data[ 0 ], data[ 1 ] )-->即是调用aaa()
*/
memory = false; // To prevent further calls using add
break;
}
}
firing = false;//循环结束后,表示触发过程已经结束了
if ( list ) {
if ( stack ) {
if ( stack.length ) {
fire( stack.shift() );
}
} else if ( memory ) {//这种情况是有传递once和memory的情况
list = [];
} else {
self.disable();//阻止后面的操作
}
}
},
// Actual Callbacks object
self = {
// Add a callback or a collection of callbacks to the list
add: function() {
if ( list ) {
// First, we save the current length
var start = list.length;
(function add( args ) {
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 ) {
/*
*第一次调用add的时候,创建Callbacks对象的时候不管是否有memory这个参数,这个时候if里面的memory都是false
*只有在调用过一次fire()方法后,并且创建Callbacks对象的时候有memory这个参数,这时候memory才是true,相当于下面的用法的时候,触发了这一块
*var cb = $.Callbacks('memory'); cb.add(params); cb.fire(); cb.add(params);-->第二个add方法会触发一次fire()
*/
firingStart = start;
fire( memory );
}
}
return this;
},
// Remove a callback from the list
remove: function() {
if ( list ) {
jQuery.each( arguments, function( _, arg ) {
var index;
while( ( index = jQuery.inArray( arg, list, index ) ) > -1 ) {
list.splice( index, 1 );
// Handle firing indexes
if ( 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 list
empty: function() {
list = [];
firingLength = 0;
return this;
},
// Have the list do nothing anymore
disable: function() {
list = stack = memory = undefined;//禁止所有的操作
return this;
},
// Is it disabled?
disabled: function() {
return !list;
},
// Lock the list in its current state
lock: function() {
stack = undefined;//只是锁住数组
if ( !memory ) {
self.disable();
}
return this;
},
// Is it locked?
locked: function() {
return !stack;
},
// Call all callbacks with the given context and arguments
fireWith: function( context, args ) {//context: 作用域,args:参数
if ( list && ( !fired || stack ) ) {
/*
*第一次调用的时候,fired为false,!false为true,那么第一次调用的时候( !fired || stack )的值就是true
*/
args = args || [];
args = [ context, args.slice ? args.slice() : args ];//将传进来的参数整成数组,好传递给fire()
if ( firing ) {
stack.push( args );
} else {
fire( args );//这时候传递给fire的args包括了具体的作用域和参数
}
}
return this;
},
// Call all the callbacks with the given arguments
fire: function() {
self.fireWith( this, arguments );
return this;
},
// To know if the callbacks have already been called at least once
fired: function() {
return !!fired;//判断是否有调用过,只要调用过一次fire()方法,都会返回true;一般函数名以ed结束,可以用来表示状态
}
};
return self;
};
/*
通过这几个实验,可以看出,JS的||并不是单纯的返回一个布尔类型。
大家都知道js的布尔类型判定是
对象是true,非零是true,非空字符串是true
其余的都是false
由此得出
逻辑或 || : var a = 表达式1 || 表达式2
表达式1 表达式2 a取值
1 0 表达式1结果值
1 1 表达式1结果值
0 1 表达式2结果值
0 0 表达式2结果值
逻辑与 && : var a = 表达式1 && 表达式2
表达式1 表达式2 a取值
1 0 表达式2结果值
1 1 表达式2结果值
0 1 表达式1结果值
0 0 表达式1结果值
主要原因是因为短路,逻辑或 || 在前面有一个ture的时候则不看后面直接停止,逻辑与&&同理。
*/
});
源码中stack是指堆栈:比如下面这种情况:
var bBtn = true;
function aaa(){
alert(1);
if(bBtn){//如果没有这个bBtn开关控制,直接在alert(1)之后执行cb.fire(),那么程序将进入死循环
cb.fire();//这种情况下,会再向stack内push函数,让要执行的函数进入队列等待执行
bBtn = false;
}
}
function bbb(){
alert(2);
}
var cb = $.Callbacks();
cb.add( aaa );
cb.add( bbb );
cb.fire();
</script>
jquery.callbacks(源码)
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转载自blog.csdn.net/rose999ying/article/details/86532874
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