Example

Using callbacks.lock() to lock a callback list to avoid further changes being made to the list state:

// a sample logging function to be added to a callbacks list
var foo = function( value ){
    console.log( 'foo:' + value);
}

var callbacks = $.Callbacks();

// add the logging function to the callback list
callbacks.add( foo );

// fire the items on the list, passing an argument
callbacks.fire( 'hello' );
// outputs 'foo: hello'

// lock the callbacks list
callbacks.lock();

// try firing the items again
callbacks.fire( 'world' );

// as the list was locked, no items
// were called so 'world' isn't logged