Added queue flag to $.Callbacks. Unit tests added (more to come).

Author: jaubourg

src/callbacks.js

@@ -34,6 +34,9 @@ function createFlags( flags ) {
  *					after the list has been fired right away with the latest "memorized"
  *					values (like a Deferred)
  *
+ *	queue:			only first callback in the list is called each time the list is fired
+ *					(cannot be used in conjunction with memory)
+ *
  *	unique:			will ensure a callback can only be added once (no duplicate in the list)
  *
  *	relocate:		like "unique" but will relocate the callback at the end of the list
@@ -112,6 +115,9 @@ jQuery.Callbacks = function( flags, filter ) {
 				if ( list[ firingIndex ][ 1 ].apply( context, args ) === false && flags.stopOnFalse ) {
 					memory = true; // Mark as halted
 					break;
+				} else if ( flags.queue ) {
+					list.splice( firingIndex, 1 );
+					break;
 				}
 			}
 			firing = false;

test/unit/callbacks.js

@@ -19,6 +19,7 @@ var output,
 		"relocate":					"XABC 	X		XAABC		X	XBB X	XBA		X",
 		"stopOnFalse":				"XABC 	X		XABCABCC	X	XBB	X	XA		X",
 		"addAfterFire":				"XAB	X		XABCAB		X	XBB	X	XABA	X",
+		"queue":					"XA		X		XB			X	XB	X	XA		X",
 		"once memory":				"XABC 	XABC	X			XA	X	XA	XABA	XC",
 		"once unique":				"XABC 	X		X			X	X	X	XAB		X",
 		"once relocate":			"XABC 	X		X			X	X	X	XBA		X",