set/remove @disabled on navigation buttons

Keeps disabled buttons out of kbd tab order and indicates to assistive
tech like screen readers that button is disabled. Otherwise buttons
that aren’t enabled remain in kbd Tab order and screen readers announce
them as buttons, but they don’t work.

1 files changed, 15 insertions, 13 deletions

diff --git a/js/reveal.js b/js/reveal.js
index 10c609e..b3a91b3 100644
--- a/js/reveal.js
+++ b/js/reveal.js
@@ -2652,34 +2652,36 @@
 						.concat( dom.controlsNext ).forEach( function( node ) {
 			node.classList.remove( 'enabled' );
 			node.classList.remove( 'fragmented' );
+			// Set 'disabled' attribute on all directions
+			node.setAttribute('disabled', 'disabled');
 		} );
 
-		// Add the 'enabled' class to the available routes
-		if( routes.left ) dom.controlsLeft.forEach( function( el ) { el.classList.add( 'enabled' );	} );
-		if( routes.right ) dom.controlsRight.forEach( function( el ) { el.classList.add( 'enabled' ); } );
-		if( routes.up ) dom.controlsUp.forEach( function( el ) { el.classList.add( 'enabled' );	} );
-		if( routes.down ) dom.controlsDown.forEach( function( el ) { el.classList.add( 'enabled' ); } );
+		// Add the 'enabled' class to the available routes; remove 'disabled' attribute to enable buttons
+		if( routes.left ) dom.controlsLeft.forEach( function( el ) { el.classList.add( 'enabled' ); el.removeAttribute('disabled');	} );
+		if( routes.right ) dom.controlsRight.forEach( function( el ) { el.classList.add( 'enabled' ); el.removeAttribute('disabled'); } );
+		if( routes.up ) dom.controlsUp.forEach( function( el ) { el.classList.add( 'enabled' ); el.removeAttribute('disabled');	} );
+		if( routes.down ) dom.controlsDown.forEach( function( el ) { el.classList.add( 'enabled' ); el.removeAttribute('disabled'); } );
 
 		// Prev/next buttons
-		if( routes.left || routes.up ) dom.controlsPrev.forEach( function( el ) { el.classList.add( 'enabled' ); } );
-		if( routes.right || routes.down ) dom.controlsNext.forEach( function( el ) { el.classList.add( 'enabled' ); } );
+		if( routes.left || routes.up ) dom.controlsPrev.forEach( function( el ) { el.classList.add( 'enabled' ); el.removeAttribute('disabled'); } );
+		if( routes.right || routes.down ) dom.controlsNext.forEach( function( el ) { el.classList.add( 'enabled' ); el.removeAttribute('disabled'); } );
 
 		// Highlight fragment directions
 		if( currentSlide ) {
 
 			// Always apply fragment decorator to prev/next buttons
-			if( fragments.prev ) dom.controlsPrev.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); } );
-			if( fragments.next ) dom.controlsNext.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); } );
+			if( fragments.prev ) dom.controlsPrev.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute('disabled'); } );
+			if( fragments.next ) dom.controlsNext.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute('disabled'); } );
 
 			// Apply fragment decorators to directional buttons based on
 			// what slide axis they are in
 			if( isVerticalSlide( currentSlide ) ) {
-				if( fragments.prev ) dom.controlsUp.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); } );
-				if( fragments.next ) dom.controlsDown.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); } );
+				if( fragments.prev ) dom.controlsUp.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute('disabled'); } );
+				if( fragments.next ) dom.controlsDown.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute('disabled'); } );
 			}
 			else {
-				if( fragments.prev ) dom.controlsLeft.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); } );
-				if( fragments.next ) dom.controlsRight.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); } );
+				if( fragments.prev ) dom.controlsLeft.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute('disabled'); } );
+				if( fragments.next ) dom.controlsRight.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute('disabled'); } );
 			}
 
 		}