+ /**
+ * @summary Add or remove ARIA attributes.
+ * Uses jQuery's width() function to determine the size of the window and add
+ * the default ARIA attributes for the menu toggle if it's visible.
+ * @since Twenty Thirteen 1.5
+ */
+ function onResizeARIA() {
+ if ( 643 > _window.width() ) {
+ button.attr( 'aria-expanded', 'false' );
+ menu.attr( 'aria-expanded', 'false' );
+ button.attr( 'aria-controls', 'primary-menu' );
+ } else {
+ button.removeAttr( 'aria-expanded' );
+ menu.removeAttr( 'aria-expanded' );
+ button.removeAttr( 'aria-controls' );
+ }
+ }
+
+ _window
+ .on( 'load.twentythirteen', onResizeARIA )
+ .on( 'resize.twentythirteen', function() {
+ onResizeARIA();
+ } );
+