jquery源码分析–$.callbacks()

先上个简单的小例子:

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function aaa(){
alert(1);
}

function bbb(){
alert(2);
}

function ccc(){
alert(3);
}

var cb = $.Callbacks();

cb.add( aaa );
cb.add( bbb );
cb.add( ccc );

cb.fire();

Callbacks的四个参数:once、memory、unique

once:fire只能触发一次(此参数作用与for循环);
memory:记忆参数,此参数作用于add方法;
unique:唯一的(去重复)此参数设置在add方法中;
stopOnFalse:此参数使return false起效果(此参数作于余额for循环)。

参数可支持组合方式

详细源码

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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 // 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 && [],
// Fire callbacks
fire = function( data ) {
memory = options.memory && data;
fired = true;
firingIndex = firingStart || 0;
firingStart = 0;
firingLength = list.length;
firing = true;
for ( ; list && firingIndex < firingLength; firingIndex++ ) {
if ( list[ firingIndex ].apply( data[ 0 ], data[ 1 ] ) === false && options.stopOnFalse ) {
memory = false; // To prevent further calls using add
break;
}
}
firing = false;
if ( list ) {
if ( stack ) {
if ( stack.length ) {
fire( stack.shift() );
}
} else if ( memory ) {
list = [];
} else {
self.disable();
}
}
},
// 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 ) {
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;
return this;
},
// Is it disabled?
disabled: function() {
return !list;
},
// Lock the list in its current state
lock: function() {
stack = undefined;
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 ) {
if ( list && ( !fired || stack ) ) {
args = args || [];
args = [ context, args.slice ? args.slice() : args ];
if ( firing ) {
stack.push( args );
} else {
fire( args );
}
}
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;
}
};

return self;
};