wikimedia/mediawiki-core

( function () {

    // Return a promise that is resolved when the element is blurred (loses focus).
    // If it already is blurred, resolved immediately.
    function whenBlurred( $elem ) {
        var deferred = $.Deferred();
        if ( $elem.is( ':focus' ) ) {
            $elem.one( 'blur', deferred.resolve );
        } else {
            deferred.resolve();
        }
        return deferred.promise();
    }

    $( function () {
        var startReady, endReady;

        // Do not infuse the date input while it has user focus.
        // This is especially important on Firefox, where hiding the native date input while the native
        // date picker is open will cause the date picker to remain visible (but non-functional), but
        // not replacing the interface while the user is working with it is probably a good idea anyway.
        startReady = whenBlurred( $( '#mw-date-start .oo-ui-inputWidget-input' ) ).then( function () {
            return mw.widgets.DateInputWidget.static.infuse( $( '#mw-date-start' ) );
        } );
        endReady = whenBlurred( $( '#mw-date-end .oo-ui-inputWidget-input' ) ).then( function () {
            return mw.widgets.DateInputWidget.static.infuse( $( '#mw-date-end' ) );
        } );

        $.when( startReady, endReady ).then( function ( startInput, endInput ) {
            startInput.on( 'deactivate', function ( userSelected ) {
                if ( userSelected ) {
                    endInput.focus();
                }
            } );
        } );
    } );

}() );