Program: CWE-79
Project: CVE-2022-0776
Buggy source:
<!--
	NOTE: You need to build the notes plugin after making changes to this file.
-->
<html lang="en">
	<head>
		<meta charset="utf-8">

		<title>reveal.js - Speaker View</title>

		<style>
			body {
				font-family: Helvetica;
				font-size: 18px;
			}

			#current-slide,
			#upcoming-slide,
			#speaker-controls {
				padding: 6px;
				box-sizing: border-box;
				-moz-box-sizing: border-box;
			}

			#current-slide iframe,
			#upcoming-slide iframe {
				width: 100%;
				height: 100%;
				border: 1px solid #ddd;
			}

			#current-slide .label,
			#upcoming-slide .label {
				position: absolute;
				top: 10px;
				left: 10px;
				z-index: 2;
			}

			#connection-status {
				position: absolute;
				top: 0;
				left: 0;
				width: 100%;
				height: 100%;
				z-index: 20;
				padding: 30% 20% 20% 20%;
				font-size: 18px;
				color: #222;
				background: #fff;
				text-align: center;
				box-sizing: border-box;
				line-height: 1.4;
			}

			.overlay-element {
				height: 34px;
				line-height: 34px;
				padding: 0 10px;
				text-shadow: none;
				background: rgba( 220, 220, 220, 0.8 );
				color: #222;
				font-size: 14px;
			}

			.overlay-element.interactive:hover {
				background: rgba( 220, 220, 220, 1 );
			}

			#current-slide {
				position: absolute;
				width: 60%;
				height: 100%;
				top: 0;
				left: 0;
				padding-right: 0;
			}

			#upcoming-slide {
				position: absolute;
				width: 40%;
				height: 40%;
				right: 0;
				top: 0;
			}

			/* Speaker controls */
			#speaker-controls {
				position: absolute;
				top: 40%;
				right: 0;
				width: 40%;
				height: 60%;
				overflow: auto;
				font-size: 18px;
			}

				.speaker-controls-time.hidden,
				.speaker-controls-notes.hidden {
					display: none;
				}

				.speaker-controls-time .label,
				.speaker-controls-pace .label,
				.speaker-controls-notes .label {
					text-transform: uppercase;
					font-weight: normal;
					font-size: 0.66em;
					color: #666;
					margin: 0;
				}

				.speaker-controls-time, .speaker-controls-pace {
					border-bottom: 1px solid rgba( 200, 200, 200, 0.5 );
					margin-bottom: 10px;
					padding: 10px 16px;
					padding-bottom: 20px;
					cursor: pointer;
				}

				.speaker-controls-time .reset-button {
					opacity: 0;
					float: right;
					color: #666;
					text-decoration: none;
				}
				.speaker-controls-time:hover .reset-button {
					opacity: 1;
				}

				.speaker-controls-time .timer,
				.speaker-controls-time .clock {
					width: 50%;
				}

				.speaker-controls-time .timer,
				.speaker-controls-time .clock,
				.speaker-controls-time .pacing .hours-value,
				.speaker-controls-time .pacing .minutes-value,
				.speaker-controls-time .pacing .seconds-value {
					font-size: 1.9em;
				}

				.speaker-controls-time .timer {
					float: left;
				}

				.speaker-controls-time .clock {
					float: right;
					text-align: right;
				}

				.speaker-controls-time span.mute {
					opacity: 0.3;
				}

				.speaker-controls-time .pacing-title {
					margin-top: 5px;
				}

				.speaker-controls-time .pacing.ahead {
					color: blue;
				}

				.speaker-controls-time .pacing.on-track {
					color: green;
				}

				.speaker-controls-time .pacing.behind {
					color: red;
				}

				.speaker-controls-notes {
					padding: 10px 16px;
				}

				.speaker-controls-notes .value {
					margin-top: 5px;
					line-height: 1.4;
					font-size: 1.2em;
				}

			/* Layout selector */
			#speaker-layout {
				position: absolute;
				top: 10px;
				right: 10px;
				color: #222;
				z-index: 10;
			}
				#speaker-layout select {
					position: absolute;
					width: 100%;
					height: 100%;
					top: 0;
					left: 0;
					border: 0;
					box-shadow: 0;
					cursor: pointer;
					opacity: 0;

					font-size: 1em;
					background-color: transparent;

					-moz-appearance: none;
					-webkit-appearance: none;
					-webkit-tap-highlight-color: rgba(0, 0, 0, 0);
				}

				#speaker-layout select:focus {
					outline: none;
					box-shadow: none;
				}

			.clear {
				clear: both;
			}

			/* Speaker layout: Wide */
			body[data-speaker-layout="wide"] #current-slide,
			body[data-speaker-layout="wide"] #upcoming-slide {
				width: 50%;
				height: 45%;
				padding: 6px;
			}

			body[data-speaker-layout="wide"] #current-slide {
				top: 0;
				left: 0;
			}

			body[data-speaker-layout="wide"] #upcoming-slide {
				top: 0;
				left: 50%;
			}

			body[data-speaker-layout="wide"] #speaker-controls {
				top: 45%;
				left: 0;
				width: 100%;
				height: 50%;
				font-size: 1.25em;
			}

			/* Speaker layout: Tall */
			body[data-speaker-layout="tall"] #current-slide,
			body[data-speaker-layout="tall"] #upcoming-slide {
				width: 45%;
				height: 50%;
				padding: 6px;
			}

			body[data-speaker-layout="tall"] #current-slide {
				top: 0;
				left: 0;
			}

			body[data-speaker-layout="tall"] #upcoming-slide {
				top: 50%;
				left: 0;
			}

			body[data-speaker-layout="tall"] #speaker-controls {
				padding-top: 40px;
				top: 0;
				left: 45%;
				width: 55%;
				height: 100%;
				font-size: 1.25em;
			}

			/* Speaker layout: Notes only */
			body[data-speaker-layout="notes-only"] #current-slide,
			body[data-speaker-layout="notes-only"] #upcoming-slide {
				display: none;
			}

			body[data-speaker-layout="notes-only"] #speaker-controls {
				padding-top: 40px;
				top: 0;
				left: 0;
				width: 100%;
				height: 100%;
				font-size: 1.25em;
			}

			@media screen and (max-width: 1080px) {
				body[data-speaker-layout="default"] #speaker-controls {
					font-size: 16px;
				}
			}

			@media screen and (max-width: 900px) {
				body[data-speaker-layout="default"] #speaker-controls {
					font-size: 14px;
				}
			}

			@media screen and (max-width: 800px) {
				body[data-speaker-layout="default"] #speaker-controls {
					font-size: 12px;
				}
			}

		</style>
	</head>

	<body>

		<div id="connection-status">Loading speaker view...</div>

		<div id="current-slide"></div>
		<div id="upcoming-slide"><span class="overlay-element label">Upcoming</span></div>
		<div id="speaker-controls">
			<div class="speaker-controls-time">
				<h4 class="label">Time <span class="reset-button">Click to Reset</span></h4>
				<div class="clock">
					<span class="clock-value">0:00 AM</span>
				</div>
				<div class="timer">
					<span class="hours-value">00</span><span class="minutes-value">:00</span><span class="seconds-value">:00</span>
				</div>
				<div class="clear"></div>

				<h4 class="label pacing-title" style="display: none">Pacing – Time to finish current slide</h4>
				<div class="pacing" style="display: none">
					<span class="hours-value">00</span><span class="minutes-value">:00</span><span class="seconds-value">:00</span>
				</div>
			</div>

			<div class="speaker-controls-notes hidden">
				<h4 class="label">Notes</h4>
				<div class="value"></div>
			</div>
		</div>
		<div id="speaker-layout" class="overlay-element interactive">
			<span class="speaker-layout-label"></span>
			<select class="speaker-layout-dropdown"></select>
		</div>

		<script>

			(function() {

				var notes,
					notesValue,
					currentState,
					currentSlide,
					upcomingSlide,
					layoutLabel,
					layoutDropdown,
					pendingCalls = {},
					lastRevealApiCallId = 0,
					connected = false;

				var SPEAKER_LAYOUTS = {
					'default': 'Default',
					'wide': 'Wide',
					'tall': 'Tall',
					'notes-only': 'Notes only'
				};

				setupLayout();

				var connectionStatus = document.querySelector( '#connection-status' );
				var connectionTimeout = setTimeout( function() {
					connectionStatus.innerHTML = 'Error connecting to main window.<br>Please try closing and reopening the speaker view.';
				}, 5000 );

				window.addEventListener( 'message', function( event ) {

					clearTimeout( connectionTimeout );
					connectionStatus.style.display = 'none';

					var data = JSON.parse( event.data );

					// The overview mode is only useful to the reveal.js instance
					// where navigation occurs so we don't sync it
					if( data.state ) delete data.state.overview;

					// Messages sent by the notes plugin inside of the main window
					if( data && data.namespace === 'reveal-notes' ) {
						if( data.type === 'connect' ) {
							handleConnectMessage( data );
						}
						else if( data.type === 'state' ) {
							handleStateMessage( data );
						}
						else if( data.type === 'return' ) {
							pendingCalls[data.callId](data.result);
							delete pendingCalls[data.callId];
						}
					}
					// Messages sent by the reveal.js inside of the current slide preview
					else if( data && data.namespace === 'reveal' ) {
						if( /ready/.test( data.eventName ) ) {
							// Send a message back to notify that the handshake is complete
							window.opener.postMessage( JSON.stringify({ namespace: 'reveal-notes', type: 'connected'} ), '*' );
						}
						else if( /slidechanged|fragmentshown|fragmenthidden|paused|resumed/.test( data.eventName ) && currentState !== JSON.stringify( data.state ) ) {

							window.opener.postMessage( JSON.stringify({ method: 'setState', args: [ data.state ]} ), '*' );

						}
					}

				} );

				/**
				 * Asynchronously calls the Reveal.js API of the main frame.
				 */
				function callRevealApi( methodName, methodArguments, callback ) {

					var callId = ++lastRevealApiCallId;
					pendingCalls[callId] = callback;
					window.opener.postMessage( JSON.stringify( {
						namespace: 'reveal-notes',
						type: 'call',
						callId: callId,
						methodName: methodName,
						arguments: methodArguments
					} ), '*' );

				}

				/**
				 * Called when the main window is trying to establish a
				 * connection.
				 */
				function handleConnectMessage( data ) {

					if( connected === false ) {
						connected = true;

						setupIframes( data );
						setupKeyboard();
						setupNotes();
						setupTimer();
						setupHeartbeat();
					}

				}

				/**
				 * Called when the main window sends an updated state.
				 */
				function handleStateMessage( data ) {

					// Store the most recently set state to avoid circular loops
					// applying the same state
					currentState = JSON.stringify( data.state );

					// No need for updating the notes in case of fragment changes
					if ( data.notes ) {
						notes.classList.remove( 'hidden' );
						notesValue.style.whiteSpace = data.whitespace;
						if( data.markdown ) {
							notesValue.innerHTML = marked( data.notes );
						}
						else {
							notesValue.innerHTML = data.notes;
						}
					}
					else {
						notes.classList.add( 'hidden' );
					}

					// Update the note slides
					currentSlide.contentWindow.postMessage( JSON.stringify({ method: 'setState', args: [ data.state ] }), '*' );
					upcomingSlide.contentWindow.postMessage( JSON.stringify({ method: 'setState', args: [ data.state ] }), '*' );
					upcomingSlide.contentWindow.postMessage( JSON.stringify({ method: 'next' }), '*' );

				}

				// Limit to max one state update per X ms
				handleStateMessage = debounce( handleStateMessage, 200 );

				/**
				 * Forward keyboard events to the current slide window.
				 * This enables keyboard events to work even if focus
				 * isn't set on the current slide iframe.
				 *
				 * Block F5 default handling, it reloads and disconnects
				 * the speaker notes window.
				 */
				function setupKeyboard() {

					document.addEventListener( 'keydown', function( event ) {
						if( event.keyCode === 116 || ( event.metaKey && event.keyCode === 82 ) ) {
							event.preventDefault();
							return false;
						}
						currentSlide.contentWindow.postMessage( JSON.stringify({ method: 'triggerKey', args: [ event.keyCode ] }), '*' );
					} );

				}

				/**
				 * Creates the preview iframes.
				 */
				function setupIframes( data ) {

					var params = [
						'receiver',
						'progress=false',
						'history=false',
						'transition=none',
						'autoSlide=0',
						'backgroundTransition=none'
					].join( '&' );

					var urlSeparator = /\?/.test(data.url) ? '&' : '?';
					var hash = '#/' + data.state.indexh + '/' + data.state.indexv;
					var currentURL = data.url + urlSeparator + params + '&postMessageEvents=true' + hash;
					var upcomingURL = data.url + urlSeparator + params + '&controls=false' + hash;

					currentSlide = document.createElement( 'iframe' );
					currentSlide.setAttribute( 'width', 1280 );
					currentSlide.setAttribute( 'height', 1024 );
					currentSlide.setAttribute( 'src', currentURL );
					document.querySelector( '#current-slide' ).appendChild( currentSlide );

					upcomingSlide = document.createElement( 'iframe' );
					upcomingSlide.setAttribute( 'width', 640 );
					upcomingSlide.setAttribute( 'height', 512 );
					upcomingSlide.setAttribute( 'src', upcomingURL );
					document.querySelector( '#upcoming-slide' ).appendChild( upcomingSlide );

				}

				/**
				 * Setup the notes UI.
				 */
				function setupNotes() {

					notes = document.querySelector( '.speaker-controls-notes' );
					notesValue = document.querySelector( '.speaker-controls-notes .value' );

				}

				/**
				 * We send out a heartbeat at all times to ensure we can
				 * reconnect with the main presentation window after reloads.
				 */
				function setupHeartbeat() {

					setInterval( () => {
						window.opener.postMessage( JSON.stringify({ namespace: 'reveal-notes', type: 'heartbeat'} ), '*' );
					}, 1000 );

				}

				function getTimings( callback ) {

					callRevealApi( 'getSlidesAttributes', [], function ( slideAttributes ) {
						callRevealApi( 'getConfig', [], function ( config ) {
							var totalTime = config.totalTime;
							var minTimePerSlide = config.minimumTimePerSlide || 0;
							var defaultTiming = config.defaultTiming;
							if ((defaultTiming == null) && (totalTime == null)) {
								callback(null);
								return;
							}
							// Setting totalTime overrides defaultTiming
							if (totalTime) {
								defaultTiming = 0;
							}
							var timings = [];
							for ( var i in slideAttributes ) {
								var slide = slideAttributes[ i ];
								var timing = defaultTiming;
								if( slide.hasOwnProperty( 'data-timing' )) {
									var t = slide[ 'data-timing' ];
									timing = parseInt(t);
									if( isNaN(timing) ) {
										console.warn("Could not parse timing '" + t + "' of slide " + i + "; using default of " + defaultTiming);
										timing = defaultTiming;
									}
								}
								timings.push(timing);
							}
							if ( totalTime ) {
								// After we've allocated time to individual slides, we summarize it and
								// subtract it from the total time
								var remainingTime = totalTime - timings.reduce( function(a, b) { return a + b; }, 0 );
								// The remaining time is divided by the number of slides that have 0 seconds
								// allocated at the moment, giving the average time-per-slide on the remaining slides
								var remainingSlides = (timings.filter( function(x) { return x == 0 }) ).length
								var timePerSlide = Math.round( remainingTime / remainingSlides, 0 )
								// And now we replace every zero-value timing with that average
								timings = timings.map( function(x) { return (x==0 ? timePerSlide : x) } );
							}
							var slidesUnderMinimum = timings.filter( function(x) { return (x < minTimePerSlide) } ).length
							if ( slidesUnderMinimum ) {
								message = "The pacing time for " + slidesUnderMinimum + " slide(s) is under the configured minimum of " + minTimePerSlide + " seconds. Check the data-timing attribute on individual slides, or consider increasing the totalTime or minimumTimePerSlide configuration options (or removing some slides).";
								alert(message);
							}
							callback( timings );
						} );
					} );

				}

				/**
				 * Return the number of seconds allocated for presenting
				 * all slides up to and including this one.
				 */
				function getTimeAllocated( timings, callback ) {

					callRevealApi( 'getSlidePastCount', [], function ( currentSlide ) {
						var allocated = 0;
						for (var i in timings.slice(0, currentSlide + 1)) {
							allocated += timings[i];
						}
						callback( allocated );
					} );

				}

				/**
				 * Create the timer and clock and start updating them
				 * at an interval.
				 */
				function setupTimer() {

					var start = new Date(),
					timeEl = document.querySelector( '.speaker-controls-time' ),
					clockEl = timeEl.querySelector( '.clock-value' ),
					hoursEl = timeEl.querySelector( '.hours-value' ),
					minutesEl = timeEl.querySelector( '.minutes-value' ),
					secondsEl = timeEl.querySelector( '.seconds-value' ),
					pacingTitleEl = timeEl.querySelector( '.pacing-title' ),
					pacingEl = timeEl.querySelector( '.pacing' ),
					pacingHoursEl = pacingEl.querySelector( '.hours-value' ),
					pacingMinutesEl = pacingEl.querySelector( '.minutes-value' ),
					pacingSecondsEl = pacingEl.querySelector( '.seconds-value' );

					var timings = null;
					getTimings( function ( _timings ) {

						timings = _timings;
						if (_timings !== null) {
							pacingTitleEl.style.removeProperty('display');
							pacingEl.style.removeProperty('display');
						}

						// Update once directly
						_updateTimer();

						// Then update every second
						setInterval( _updateTimer, 1000 );

					} );


					function _resetTimer() {

						if (timings == null) {
							start = new Date();
							_updateTimer();
						}
						else {
							// Reset timer to beginning of current slide
							getTimeAllocated( timings, function ( slideEndTimingSeconds ) {
								var slideEndTiming = slideEndTimingSeconds * 1000;
								callRevealApi( 'getSlidePastCount', [], function ( currentSlide ) {
									var currentSlideTiming = timings[currentSlide] * 1000;
									var previousSlidesTiming = slideEndTiming - currentSlideTiming;
									var now = new Date();
									start = new Date(now.getTime() - previousSlidesTiming);
									_updateTimer();
								} );
							} );
						}

					}

					timeEl.addEventListener( 'click', function() {
						_resetTimer();
						return false;
					} );

					function _displayTime( hrEl, minEl, secEl, time) {

						var sign = Math.sign(time) == -1 ? "-" : "";
						time = Math.abs(Math.round(time / 1000));
						var seconds = time % 60;
						var minutes = Math.floor( time / 60 ) % 60 ;
						var hours = Math.floor( time / ( 60 * 60 )) ;
						hrEl.innerHTML = sign + zeroPadInteger( hours );
						if (hours == 0) {
							hrEl.classList.add( 'mute' );
						}
						else {
							hrEl.classList.remove( 'mute' );
						}
						minEl.innerHTML = ':' + zeroPadInteger( minutes );
						if (hours == 0 && minutes == 0) {
							minEl.classList.add( 'mute' );
						}
						else {
							minEl.classList.remove( 'mute' );
						}
						secEl.innerHTML = ':' + zeroPadInteger( seconds );
					}

					function _updateTimer() {

						var diff, hours, minutes, seconds,
						now = new Date();

						diff = now.getTime() - start.getTime();

						clockEl.innerHTML = now.toLocaleTimeString( 'en-US', { hour12: true, hour: '2-digit', minute:'2-digit' } );
						_displayTime( hoursEl, minutesEl, secondsEl, diff );
						if (timings !== null) {
							_updatePacing(diff);
						}

					}

					function _updatePacing(diff) {

						getTimeAllocated( timings, function ( slideEndTimingSeconds ) {
							var slideEndTiming = slideEndTimingSeconds * 1000;

							callRevealApi( 'getSlidePastCount', [], function ( currentSlide ) {
								var currentSlideTiming = timings[currentSlide] * 1000;
								var timeLeftCurrentSlide = slideEndTiming - diff;
								if (timeLeftCurrentSlide < 0) {
									pacingEl.className = 'pacing behind';
								}
								else if (timeLeftCurrentSlide < currentSlideTiming) {
									pacingEl.className = 'pacing on-track';
								}
								else {
									pacingEl.className = 'pacing ahead';
								}
								_displayTime( pacingHoursEl, pacingMinutesEl, pacingSecondsEl, timeLeftCurrentSlide );
							} );
						} );
					}

				}

				/**
				 * Sets up the speaker view layout and layout selector.
				 */
				function setupLayout() {

					layoutDropdown = document.querySelector( '.speaker-layout-dropdown' );
					layoutLabel = document.querySelector( '.speaker-layout-label' );

					// Render the list of available layouts
					for( var id in SPEAKER_LAYOUTS ) {
						var option = document.createElement( 'option' );
						option.setAttribute( 'value', id );
						option.textContent = SPEAKER_LAYOUTS[ id ];
						layoutDropdown.appendChild( option );
					}

					// Monitor the dropdown for changes
					layoutDropdown.addEventListener( 'change', function( event ) {

						setLayout( layoutDropdown.value );

					}, false );

					// Restore any currently persisted layout
					setLayout( getLayout() );

				}

				/**
				 * Sets a new speaker view layout. The layout is persisted
				 * in local storage.
				 */
				function setLayout( value ) {

					var title = SPEAKER_LAYOUTS[ value ];

					layoutLabel.innerHTML = 'Layout' + ( title ? ( ': ' + title ) : '' );
					layoutDropdown.value = value;

					document.body.setAttribute( 'data-speaker-layout', value );

					// Persist locally
					if( supportsLocalStorage() ) {
						window.localStorage.setItem( 'reveal-speaker-layout', value );
					}

				}

				/**
				 * Returns the ID of the most recently set speaker layout
				 * or our default layout if none has been set.
				 */
				function getLayout() {

					if( supportsLocalStorage() ) {
						var layout = window.localStorage.getItem( 'reveal-speaker-layout' );
						if( layout ) {
							return layout;
						}
					}

					// Default to the first record in the layouts hash
					for( var id in SPEAKER_LAYOUTS ) {
						return id;
					}

				}

				function supportsLocalStorage() {

					try {
						localStorage.setItem('test', 'test');
						localStorage.removeItem('test');
						return true;
					}
					catch( e ) {
						return false;
					}

				}

				function zeroPadInteger( num ) {

					var str = '00' + parseInt( num );
					return str.substring( str.length - 2 );

				}

				/**
				 * Limits the frequency at which a function can be called.
				 */
				function debounce( fn, ms ) {

					var lastTime = 0,
						timeout;

					return function() {

						var args = arguments;
						var context = this;

						clearTimeout( timeout );

						var timeSinceLastCall = Date.now() - lastTime;
						if( timeSinceLastCall > ms ) {
							fn.apply( context, args );
							lastTime = Date.now();
						}
						else {
							timeout = setTimeout( function() {
								fn.apply( context, args );
								lastTime = Date.now();
							}, ms - timeSinceLastCall );
						}

					}

				}

			})();

		</script>
	</body>
</html>

Fixed version (ground truth):
<!--
	NOTE: You need to build the notes plugin after making changes to this file.
-->
<html lang="en">
	<head>
		<meta charset="utf-8">

		<title>reveal.js - Speaker View</title>

		<style>
			body {
				font-family: Helvetica;
				font-size: 18px;
			}

			#current-slide,
			#upcoming-slide,
			#speaker-controls {
				padding: 6px;
				box-sizing: border-box;
				-moz-box-sizing: border-box;
			}

			#current-slide iframe,
			#upcoming-slide iframe {
				width: 100%;
				height: 100%;
				border: 1px solid #ddd;
			}

			#current-slide .label,
			#upcoming-slide .label {
				position: absolute;
				top: 10px;
				left: 10px;
				z-index: 2;
			}

			#connection-status {
				position: absolute;
				top: 0;
				left: 0;
				width: 100%;
				height: 100%;
				z-index: 20;
				padding: 30% 20% 20% 20%;
				font-size: 18px;
				color: #222;
				background: #fff;
				text-align: center;
				box-sizing: border-box;
				line-height: 1.4;
			}

			.overlay-element {
				height: 34px;
				line-height: 34px;
				padding: 0 10px;
				text-shadow: none;
				background: rgba( 220, 220, 220, 0.8 );
				color: #222;
				font-size: 14px;
			}

			.overlay-element.interactive:hover {
				background: rgba( 220, 220, 220, 1 );
			}

			#current-slide {
				position: absolute;
				width: 60%;
				height: 100%;
				top: 0;
				left: 0;
				padding-right: 0;
			}

			#upcoming-slide {
				position: absolute;
				width: 40%;
				height: 40%;
				right: 0;
				top: 0;
			}

			/* Speaker controls */
			#speaker-controls {
				position: absolute;
				top: 40%;
				right: 0;
				width: 40%;
				height: 60%;
				overflow: auto;
				font-size: 18px;
			}

				.speaker-controls-time.hidden,
				.speaker-controls-notes.hidden {
					display: none;
				}

				.speaker-controls-time .label,
				.speaker-controls-pace .label,
				.speaker-controls-notes .label {
					text-transform: uppercase;
					font-weight: normal;
					font-size: 0.66em;
					color: #666;
					margin: 0;
				}

				.speaker-controls-time, .speaker-controls-pace {
					border-bottom: 1px solid rgba( 200, 200, 200, 0.5 );
					margin-bottom: 10px;
					padding: 10px 16px;
					padding-bottom: 20px;
					cursor: pointer;
				}

				.speaker-controls-time .reset-button {
					opacity: 0;
					float: right;
					color: #666;
					text-decoration: none;
				}
				.speaker-controls-time:hover .reset-button {
					opacity: 1;
				}

				.speaker-controls-time .timer,
				.speaker-controls-time .clock {
					width: 50%;
				}

				.speaker-controls-time .timer,
				.speaker-controls-time .clock,
				.speaker-controls-time .pacing .hours-value,
				.speaker-controls-time .pacing .minutes-value,
				.speaker-controls-time .pacing .seconds-value {
					font-size: 1.9em;
				}

				.speaker-controls-time .timer {
					float: left;
				}

				.speaker-controls-time .clock {
					float: right;
					text-align: right;
				}

				.speaker-controls-time span.mute {
					opacity: 0.3;
				}

				.speaker-controls-time .pacing-title {
					margin-top: 5px;
				}

				.speaker-controls-time .pacing.ahead {
					color: blue;
				}

				.speaker-controls-time .pacing.on-track {
					color: green;
				}

				.speaker-controls-time .pacing.behind {
					color: red;
				}

				.speaker-controls-notes {
					padding: 10px 16px;
				}

				.speaker-controls-notes .value {
					margin-top: 5px;
					line-height: 1.4;
					font-size: 1.2em;
				}

			/* Layout selector */
			#speaker-layout {
				position: absolute;
				top: 10px;
				right: 10px;
				color: #222;
				z-index: 10;
			}
				#speaker-layout select {
					position: absolute;
					width: 100%;
					height: 100%;
					top: 0;
					left: 0;
					border: 0;
					box-shadow: 0;
					cursor: pointer;
					opacity: 0;

					font-size: 1em;
					background-color: transparent;

					-moz-appearance: none;
					-webkit-appearance: none;
					-webkit-tap-highlight-color: rgba(0, 0, 0, 0);
				}

				#speaker-layout select:focus {
					outline: none;
					box-shadow: none;
				}

			.clear {
				clear: both;
			}

			/* Speaker layout: Wide */
			body[data-speaker-layout="wide"] #current-slide,
			body[data-speaker-layout="wide"] #upcoming-slide {
				width: 50%;
				height: 45%;
				padding: 6px;
			}

			body[data-speaker-layout="wide"] #current-slide {
				top: 0;
				left: 0;
			}

			body[data-speaker-layout="wide"] #upcoming-slide {
				top: 0;
				left: 50%;
			}

			body[data-speaker-layout="wide"] #speaker-controls {
				top: 45%;
				left: 0;
				width: 100%;
				height: 50%;
				font-size: 1.25em;
			}

			/* Speaker layout: Tall */
			body[data-speaker-layout="tall"] #current-slide,
			body[data-speaker-layout="tall"] #upcoming-slide {
				width: 45%;
				height: 50%;
				padding: 6px;
			}

			body[data-speaker-layout="tall"] #current-slide {
				top: 0;
				left: 0;
			}

			body[data-speaker-layout="tall"] #upcoming-slide {
				top: 50%;
				left: 0;
			}

			body[data-speaker-layout="tall"] #speaker-controls {
				padding-top: 40px;
				top: 0;
				left: 45%;
				width: 55%;
				height: 100%;
				font-size: 1.25em;
			}

			/* Speaker layout: Notes only */
			body[data-speaker-layout="notes-only"] #current-slide,
			body[data-speaker-layout="notes-only"] #upcoming-slide {
				display: none;
			}

			body[data-speaker-layout="notes-only"] #speaker-controls {
				padding-top: 40px;
				top: 0;
				left: 0;
				width: 100%;
				height: 100%;
				font-size: 1.25em;
			}

			@media screen and (max-width: 1080px) {
				body[data-speaker-layout="default"] #speaker-controls {
					font-size: 16px;
				}
			}

			@media screen and (max-width: 900px) {
				body[data-speaker-layout="default"] #speaker-controls {
					font-size: 14px;
				}
			}

			@media screen and (max-width: 800px) {
				body[data-speaker-layout="default"] #speaker-controls {
					font-size: 12px;
				}
			}

		</style>
	</head>

	<body>

		<div id="connection-status">Loading speaker view...</div>

		<div id="current-slide"></div>
		<div id="upcoming-slide"><span class="overlay-element label">Upcoming</span></div>
		<div id="speaker-controls">
			<div class="speaker-controls-time">
				<h4 class="label">Time <span class="reset-button">Click to Reset</span></h4>
				<div class="clock">
					<span class="clock-value">0:00 AM</span>
				</div>
				<div class="timer">
					<span class="hours-value">00</span><span class="minutes-value">:00</span><span class="seconds-value">:00</span>
				</div>
				<div class="clear"></div>

				<h4 class="label pacing-title" style="display: none">Pacing – Time to finish current slide</h4>
				<div class="pacing" style="display: none">
					<span class="hours-value">00</span><span class="minutes-value">:00</span><span class="seconds-value">:00</span>
				</div>
			</div>

			<div class="speaker-controls-notes hidden">
				<h4 class="label">Notes</h4>
				<div class="value"></div>
			</div>
		</div>
		<div id="speaker-layout" class="overlay-element interactive">
			<span class="speaker-layout-label"></span>
			<select class="speaker-layout-dropdown"></select>
		</div>

		<script>

			(function() {

				var notes,
					notesValue,
					currentState,
					currentSlide,
					upcomingSlide,
					layoutLabel,
					layoutDropdown,
					pendingCalls = {},
					lastRevealApiCallId = 0,
					connected = false;

				var SPEAKER_LAYOUTS = {
					'default': 'Default',
					'wide': 'Wide',
					'tall': 'Tall',
					'notes-only': 'Notes only'
				};

				setupLayout();

				var connectionStatus = document.querySelector( '#connection-status' );
				var connectionTimeout = setTimeout( function() {
					connectionStatus.innerHTML = 'Error connecting to main window.<br>Please try closing and reopening the speaker view.';
				}, 5000 );

				window.addEventListener( 'message', function( event ) {

					if (window.location.origin !== event.origin){
						return;
					}

					clearTimeout( connectionTimeout );
					connectionStatus.style.display = 'none';

					var data = JSON.parse( event.data );

					// The overview mode is only useful to the reveal.js instance
					// where navigation occurs so we don't sync it
					if( data.state ) delete data.state.overview;

					// Messages sent by the notes plugin inside of the main window
					if( data && data.namespace === 'reveal-notes' ) {
						if( data.type === 'connect' ) {
							handleConnectMessage( data );
						}
						else if( data.type === 'state' ) {
							handleStateMessage( data );
						}
						else if( data.type === 'return' ) {
							pendingCalls[data.callId](data.result);
							delete pendingCalls[data.callId];
						}
					}
					// Messages sent by the reveal.js inside of the current slide preview
					else if( data && data.namespace === 'reveal' ) {
						if( /ready/.test( data.eventName ) ) {
							// Send a message back to notify that the handshake is complete
							window.opener.postMessage( JSON.stringify({ namespace: 'reveal-notes', type: 'connected'} ), '*' );
						}
						else if( /slidechanged|fragmentshown|fragmenthidden|paused|resumed/.test( data.eventName ) && currentState !== JSON.stringify( data.state ) ) {

							window.opener.postMessage( JSON.stringify({ method: 'setState', args: [ data.state ]} ), '*' );

						}
					}

				} );

				/**
				 * Asynchronously calls the Reveal.js API of the main frame.
				 */
				function callRevealApi( methodName, methodArguments, callback ) {

					var callId = ++lastRevealApiCallId;
					pendingCalls[callId] = callback;
					window.opener.postMessage( JSON.stringify( {
						namespace: 'reveal-notes',
						type: 'call',
						callId: callId,
						methodName: methodName,
						arguments: methodArguments
					} ), '*' );

				}

				/**
				 * Called when the main window is trying to establish a
				 * connection.
				 */
				function handleConnectMessage( data ) {

					if( connected === false ) {
						connected = true;

						setupIframes( data );
						setupKeyboard();
						setupNotes();
						setupTimer();
						setupHeartbeat();
					}

				}

				/**
				 * Called when the main window sends an updated state.
				 */
				function handleStateMessage( data ) {

					// Store the most recently set state to avoid circular loops
					// applying the same state
					currentState = JSON.stringify( data.state );

					// No need for updating the notes in case of fragment changes
					if ( data.notes ) {
						notes.classList.remove( 'hidden' );
						notesValue.style.whiteSpace = data.whitespace;
						if( data.markdown ) {
							notesValue.innerHTML = marked( data.notes );
						}
						else {
							notesValue.innerHTML = data.notes;
						}
					}
					else {
						notes.classList.add( 'hidden' );
					}

					// Update the note slides
					currentSlide.contentWindow.postMessage( JSON.stringify({ method: 'setState', args: [ data.state ] }), '*' );
					upcomingSlide.contentWindow.postMessage( JSON.stringify({ method: 'setState', args: [ data.state ] }), '*' );
					upcomingSlide.contentWindow.postMessage( JSON.stringify({ method: 'next' }), '*' );

				}

				// Limit to max one state update per X ms
				handleStateMessage = debounce( handleStateMessage, 200 );

				/**
				 * Forward keyboard events to the current slide window.
				 * This enables keyboard events to work even if focus
				 * isn't set on the current slide iframe.
				 *
				 * Block F5 default handling, it reloads and disconnects
				 * the speaker notes window.
				 */
				function setupKeyboard() {

					document.addEventListener( 'keydown', function( event ) {
						if( event.keyCode === 116 || ( event.metaKey && event.keyCode === 82 ) ) {
							event.preventDefault();
							return false;
						}
						currentSlide.contentWindow.postMessage( JSON.stringify({ method: 'triggerKey', args: [ event.keyCode ] }), '*' );
					} );

				}

				/**
				 * Creates the preview iframes.
				 */
				function setupIframes( data ) {

					var params = [
						'receiver',
						'progress=false',
						'history=false',
						'transition=none',
						'autoSlide=0',
						'backgroundTransition=none'
					].join( '&' );

					var urlSeparator = /\?/.test(data.url) ? '&' : '?';
					var hash = '#/' + data.state.indexh + '/' + data.state.indexv;
					var currentURL = data.url + urlSeparator + params + '&postMessageEvents=true' + hash;
					var upcomingURL = data.url + urlSeparator + params + '&controls=false' + hash;

					currentSlide = document.createElement( 'iframe' );
					currentSlide.setAttribute( 'width', 1280 );
					currentSlide.setAttribute( 'height', 1024 );
					currentSlide.setAttribute( 'src', currentURL );
					document.querySelector( '#current-slide' ).appendChild( currentSlide );

					upcomingSlide = document.createElement( 'iframe' );
					upcomingSlide.setAttribute( 'width', 640 );
					upcomingSlide.setAttribute( 'height', 512 );
					upcomingSlide.setAttribute( 'src', upcomingURL );
					document.querySelector( '#upcoming-slide' ).appendChild( upcomingSlide );

				}

				/**
				 * Setup the notes UI.
				 */
				function setupNotes() {

					notes = document.querySelector( '.speaker-controls-notes' );
					notesValue = document.querySelector( '.speaker-controls-notes .value' );

				}

				/**
				 * We send out a heartbeat at all times to ensure we can
				 * reconnect with the main presentation window after reloads.
				 */
				function setupHeartbeat() {

					setInterval( () => {
						window.opener.postMessage( JSON.stringify({ namespace: 'reveal-notes', type: 'heartbeat'} ), '*' );
					}, 1000 );

				}

				function getTimings( callback ) {

					callRevealApi( 'getSlidesAttributes', [], function ( slideAttributes ) {
						callRevealApi( 'getConfig', [], function ( config ) {
							var totalTime = config.totalTime;
							var minTimePerSlide = config.minimumTimePerSlide || 0;
							var defaultTiming = config.defaultTiming;
							if ((defaultTiming == null) && (totalTime == null)) {
								callback(null);
								return;
							}
							// Setting totalTime overrides defaultTiming
							if (totalTime) {
								defaultTiming = 0;
							}
							var timings = [];
							for ( var i in slideAttributes ) {
								var slide = slideAttributes[ i ];
								var timing = defaultTiming;
								if( slide.hasOwnProperty( 'data-timing' )) {
									var t = slide[ 'data-timing' ];
									timing = parseInt(t);
									if( isNaN(timing) ) {
										console.warn("Could not parse timing '" + t + "' of slide " + i + "; using default of " + defaultTiming);
										timing = defaultTiming;
									}
								}
								timings.push(timing);
							}
							if ( totalTime ) {
								// After we've allocated time to individual slides, we summarize it and
								// subtract it from the total time
								var remainingTime = totalTime - timings.reduce( function(a, b) { return a + b; }, 0 );
								// The remaining time is divided by the number of slides that have 0 seconds
								// allocated at the moment, giving the average time-per-slide on the remaining slides
								var remainingSlides = (timings.filter( function(x) { return x == 0 }) ).length
								var timePerSlide = Math.round( remainingTime / remainingSlides, 0 )
								// And now we replace every zero-value timing with that average
								timings = timings.map( function(x) { return (x==0 ? timePerSlide : x) } );
							}
							var slidesUnderMinimum = timings.filter( function(x) { return (x < minTimePerSlide) } ).length
							if ( slidesUnderMinimum ) {
								message = "The pacing time for " + slidesUnderMinimum + " slide(s) is under the configured minimum of " + minTimePerSlide + " seconds. Check the data-timing attribute on individual slides, or consider increasing the totalTime or minimumTimePerSlide configuration options (or removing some slides).";
								alert(message);
							}
							callback( timings );
						} );
					} );

				}

				/**
				 * Return the number of seconds allocated for presenting
				 * all slides up to and including this one.
				 */
				function getTimeAllocated( timings, callback ) {

					callRevealApi( 'getSlidePastCount', [], function ( currentSlide ) {
						var allocated = 0;
						for (var i in timings.slice(0, currentSlide + 1)) {
							allocated += timings[i];
						}
						callback( allocated );
					} );

				}

				/**
				 * Create the timer and clock and start updating them
				 * at an interval.
				 */
				function setupTimer() {

					var start = new Date(),
					timeEl = document.querySelector( '.speaker-controls-time' ),
					clockEl = timeEl.querySelector( '.clock-value' ),
					hoursEl = timeEl.querySelector( '.hours-value' ),
					minutesEl = timeEl.querySelector( '.minutes-value' ),
					secondsEl = timeEl.querySelector( '.seconds-value' ),
					pacingTitleEl = timeEl.querySelector( '.pacing-title' ),
					pacingEl = timeEl.querySelector( '.pacing' ),
					pacingHoursEl = pacingEl.querySelector( '.hours-value' ),
					pacingMinutesEl = pacingEl.querySelector( '.minutes-value' ),
					pacingSecondsEl = pacingEl.querySelector( '.seconds-value' );

					var timings = null;
					getTimings( function ( _timings ) {

						timings = _timings;
						if (_timings !== null) {
							pacingTitleEl.style.removeProperty('display');
							pacingEl.style.removeProperty('display');
						}

						// Update once directly
						_updateTimer();

						// Then update every second
						setInterval( _updateTimer, 1000 );

					} );


					function _resetTimer() {

						if (timings == null) {
							start = new Date();
							_updateTimer();
						}
						else {
							// Reset timer to beginning of current slide
							getTimeAllocated( timings, function ( slideEndTimingSeconds ) {
								var slideEndTiming = slideEndTimingSeconds * 1000;
								callRevealApi( 'getSlidePastCount', [], function ( currentSlide ) {
									var currentSlideTiming = timings[currentSlide] * 1000;
									var previousSlidesTiming = slideEndTiming - currentSlideTiming;
									var now = new Date();
									start = new Date(now.getTime() - previousSlidesTiming);
									_updateTimer();
								} );
							} );
						}

					}

					timeEl.addEventListener( 'click', function() {
						_resetTimer();
						return false;
					} );

					function _displayTime( hrEl, minEl, secEl, time) {

						var sign = Math.sign(time) == -1 ? "-" : "";
						time = Math.abs(Math.round(time / 1000));
						var seconds = time % 60;
						var minutes = Math.floor( time / 60 ) % 60 ;
						var hours = Math.floor( time / ( 60 * 60 )) ;
						hrEl.innerHTML = sign + zeroPadInteger( hours );
						if (hours == 0) {
							hrEl.classList.add( 'mute' );
						}
						else {
							hrEl.classList.remove( 'mute' );
						}
						minEl.innerHTML = ':' + zeroPadInteger( minutes );
						if (hours == 0 && minutes == 0) {
							minEl.classList.add( 'mute' );
						}
						else {
							minEl.classList.remove( 'mute' );
						}
						secEl.innerHTML = ':' + zeroPadInteger( seconds );
					}

					function _updateTimer() {

						var diff, hours, minutes, seconds,
						now = new Date();

						diff = now.getTime() - start.getTime();

						clockEl.innerHTML = now.toLocaleTimeString( 'en-US', { hour12: true, hour: '2-digit', minute:'2-digit' } );
						_displayTime( hoursEl, minutesEl, secondsEl, diff );
						if (timings !== null) {
							_updatePacing(diff);
						}

					}

					function _updatePacing(diff) {

						getTimeAllocated( timings, function ( slideEndTimingSeconds ) {
							var slideEndTiming = slideEndTimingSeconds * 1000;

							callRevealApi( 'getSlidePastCount', [], function ( currentSlide ) {
								var currentSlideTiming = timings[currentSlide] * 1000;
								var timeLeftCurrentSlide = slideEndTiming - diff;
								if (timeLeftCurrentSlide < 0) {
									pacingEl.className = 'pacing behind';
								}
								else if (timeLeftCurrentSlide < currentSlideTiming) {
									pacingEl.className = 'pacing on-track';
								}
								else {
									pacingEl.className = 'pacing ahead';
								}
								_displayTime( pacingHoursEl, pacingMinutesEl, pacingSecondsEl, timeLeftCurrentSlide );
							} );
						} );
					}

				}

				/**
				 * Sets up the speaker view layout and layout selector.
				 */
				function setupLayout() {

					layoutDropdown = document.querySelector( '.speaker-layout-dropdown' );
					layoutLabel = document.querySelector( '.speaker-layout-label' );

					// Render the list of available layouts
					for( var id in SPEAKER_LAYOUTS ) {
						var option = document.createElement( 'option' );
						option.setAttribute( 'value', id );
						option.textContent = SPEAKER_LAYOUTS[ id ];
						layoutDropdown.appendChild( option );
					}

					// Monitor the dropdown for changes
					layoutDropdown.addEventListener( 'change', function( event ) {

						setLayout( layoutDropdown.value );

					}, false );

					// Restore any currently persisted layout
					setLayout( getLayout() );

				}

				/**
				 * Sets a new speaker view layout. The layout is persisted
				 * in local storage.
				 */
				function setLayout( value ) {

					var title = SPEAKER_LAYOUTS[ value ];

					layoutLabel.innerHTML = 'Layout' + ( title ? ( ': ' + title ) : '' );
					layoutDropdown.value = value;

					document.body.setAttribute( 'data-speaker-layout', value );

					// Persist locally
					if( supportsLocalStorage() ) {
						window.localStorage.setItem( 'reveal-speaker-layout', value );
					}

				}

				/**
				 * Returns the ID of the most recently set speaker layout
				 * or our default layout if none has been set.
				 */
				function getLayout() {

					if( supportsLocalStorage() ) {
						var layout = window.localStorage.getItem( 'reveal-speaker-layout' );
						if( layout ) {
							return layout;
						}
					}

					// Default to the first record in the layouts hash
					for( var id in SPEAKER_LAYOUTS ) {
						return id;
					}

				}

				function supportsLocalStorage() {

					try {
						localStorage.setItem('test', 'test');
						localStorage.removeItem('test');
						return true;
					}
					catch( e ) {
						return false;
					}

				}

				function zeroPadInteger( num ) {

					var str = '00' + parseInt( num );
					return str.substring( str.length - 2 );

				}

				/**
				 * Limits the frequency at which a function can be called.
				 */
				function debounce( fn, ms ) {

					var lastTime = 0,
						timeout;

					return function() {

						var args = arguments;
						var context = this;

						clearTimeout( timeout );

						var timeSinceLastCall = Date.now() - lastTime;
						if( timeSinceLastCall > ms ) {
							fn.apply( context, args );
							lastTime = Date.now();
						}
						else {
							timeout = setTimeout( function() {
								fn.apply( context, args );
								lastTime = Date.now();
							}, ms - timeSinceLastCall );
						}

					}

				}

			})();

		</script>
	</body>
</html>