Datepicker: Add option for onUpdateDatepicker callback

Add a new option named onUpdateDatepicker that allows a custom callback
to be provided. If provided, the callback is called at the end of
$.datepicker._updateDatepicker.

tests/unit/datepicker/options.js

@@ -813,7 +813,9 @@ var beforeShowThis = null,
 	beforeShowInput = null,
 	beforeShowInst = null,
 	beforeShowDayThis = null,
-	beforeShowDayOK = true;
+	beforeShowDayOK = true,
+	onUpdateDatepickerThis = null,
+	onUpdateDatepickerInst = null;
 
 function beforeAll( input, inst ) {
 	beforeShowThis = this;
@@ -830,8 +832,14 @@ function beforeDay( date ) {
 		( date.getDate() % 3 === 0 ? "Divisble by 3" : "" ) ];
 }
 
+function onUpdateDatepicker( inst ) {
+	onUpdateDatepickerThis = this;
+	onUpdateDatepickerInst = inst;
+	inst.dpDiv.append( $( "<div>" ).addClass( "on-update-datepicker-test" ) );
+}
+
 QUnit.test( "callbacks", function( assert ) {
-	assert.expect( 13 );
+	assert.expect( 16 );
 
 	// Before show
 	var dp, day20, day21,
@@ -860,6 +868,14 @@ QUnit.test( "callbacks", function( assert ) {
 	assert.ok( !day20.attr( "title" ), "Before show day - title 20" );
 	assert.ok( day21.attr( "title" ) === "Divisble by 3", "Before show day - title 21" );
 	inp.datepicker( "hide" ).datepicker( "destroy" );
+
+	inp = testHelper.init( "#inp", { onUpdateDatepicker: onUpdateDatepicker } );
+	inst = $.data( inp[ 0 ], "datepicker" );
+	dp = $( "#ui-datepicker-div" );
+	inp.val( "02/04/2008" ).datepicker( "show" );
+	assert.ok( onUpdateDatepickerThis.id === inp[ 0 ].id, "On update datepicker - this OK" );
+	assert.deepEqual( onUpdateDatepickerInst, inst, "On update datepicker - inst OK" );
+	assert.ok( dp.find( "div.on-update-datepicker-test" ).length > 0, "On update datepicker - custom element" );
 } );
 
 QUnit.test( "beforeShowDay - tooltips with quotes", function( assert ) {

ui/widgets/datepicker.js

@@ -142,6 +142,7 @@ function Datepicker() {
 		onSelect: null, // Define a callback function when a date is selected
 		onChangeMonthYear: null, // Define a callback function when the month or year is changed
 		onClose: null, // Define a callback function when the datepicker is closed
+		onUpdateDatepicker: null, // Define a callback function when the datepicker is updated
 		numberOfMonths: 1, // Number of months to show at a time
 		showCurrentAtPos: 0, // The position in multipe months at which to show the current month (starting at 0)
 		stepMonths: 1, // Number of months to step back/forward
@@ -857,7 +858,8 @@ $.extend( Datepicker.prototype, {
 			numMonths = this._getNumberOfMonths( inst ),
 			cols = numMonths[ 1 ],
 			width = 17,
-			activeCell = inst.dpDiv.find( "." + this._dayOverClass + " a" );
+			activeCell = inst.dpDiv.find( "." + this._dayOverClass + " a" ),
+			onUpdateDatepicker = $.datepicker._get( inst, "onUpdateDatepicker" );
 
 		if ( activeCell.length > 0 ) {
 			datepicker_handleMouseover.apply( activeCell.get( 0 ) );
@@ -888,6 +890,10 @@ $.extend( Datepicker.prototype, {
 				origyearshtml = inst.yearshtml = null;
 			}, 0 );
 		}
+
+		if ( onUpdateDatepicker ) {
+			onUpdateDatepicker.apply( ( inst.input ? inst.input[ 0 ] : null ), [ inst ] );
+		}
 	},
 
 	// #6694 - don't focus the input if it's already focused