load( slide, options = {} ) {

		// Show the slide element
		slide.style.display = this.Reveal.getConfig().display;

		// Media elements with data-src attributes
		queryAll( slide, 'img[data-src], video[data-src], audio[data-src], iframe[data-src]' ).forEach( element => {
			if( element.tagName !== 'IFRAME' || this.shouldPreload( element ) ) {
				element.setAttribute( 'src', element.getAttribute( 'data-src' ) );
				element.setAttribute( 'data-lazy-loaded', '' );
				element.removeAttribute( 'data-src' );
			}
		} );

		// Media elements with <source> children
		queryAll( slide, 'video, audio' ).forEach( media => {
			let sources = 0;

			queryAll( media, 'source[data-src]' ).forEach( source => {
				source.setAttribute( 'src', source.getAttribute( 'data-src' ) );
				source.removeAttribute( 'data-src' );
				source.setAttribute( 'data-lazy-loaded', '' );
				sources += 1;
			} );

			// Enable inline video playback in mobile Safari
			if( isMobile && media.tagName === 'VIDEO' ) {
				media.setAttribute( 'playsinline', '' );
			}

			// If we rewrote sources for this video/audio element, we need
			// to manually tell it to load from its new origin
			if( sources > 0 ) {
				media.load();
			}
		} );


		// Show the corresponding background element
		let background = slide.slideBackgroundElement;
		if( background ) {
			background.style.display = 'block';

			let backgroundContent = slide.slideBackgroundContentElement;
			let backgroundIframe = slide.getAttribute( 'data-background-iframe' );

			// If the background contains media, load it
			if( background.hasAttribute( 'data-loaded' ) === false ) {
				background.setAttribute( 'data-loaded', 'true' );

				let backgroundImage = slide.getAttribute( 'data-background-image' ),
					backgroundVideo = slide.getAttribute( 'data-background-video' ),
					backgroundVideoLoop = slide.hasAttribute( 'data-background-video-loop' ),
					backgroundVideoMuted = slide.hasAttribute( 'data-background-video-muted' );

				// Images
				if( backgroundImage ) {
					// base64
					if(  /^data:/.test( backgroundImage.trim() ) ) {
						backgroundContent.style.backgroundImage = `url(${backgroundImage.trim()})`;
					}
					// URL(s)
					else {
						backgroundContent.style.backgroundImage = backgroundImage.split( ',' ).map( background => {
							// Decode URL(s) that are already encoded first
							let decoded = decodeURI(background.trim());
							return `url(${encodeRFC3986URI(decoded)})`;
						}).join( ',' );
					}
				}
				// Videos
				else if ( backgroundVideo ) {
					let video = document.createElement( 'video' );

					if( backgroundVideoLoop ) {
						video.setAttribute( 'loop', '' );
					}

					if( backgroundVideoMuted || this.Reveal.isSpeakerNotes() ) {
						video.muted = true;
					}

					// Enable inline playback in mobile Safari
					//
					// Mute is required for video to play when using
					// swipe gestures to navigate since they don't
					// count as direct user actions :'(
					if( isMobile ) {
						video.muted = true;
						video.setAttribute( 'playsinline', '' );
					}

					// Support comma separated lists of video sources
					backgroundVideo.split( ',' ).forEach( source => {
						const sourceElement = document.createElement( 'source' );
						sourceElement.setAttribute( 'src', source );

						let type = getMimeTypeFromFile( source );
						if( type ) {
							sourceElement.setAttribute( 'type', type );
						}

						video.appendChild( sourceElement );
					} );

					backgroundContent.appendChild( video );
				}
				// Iframes
				else if( backgroundIframe && options.excludeIframes !== true ) {
					let iframe = document.createElement( 'iframe' );
					iframe.setAttribute( 'allowfullscreen', '' );
					iframe.setAttribute( 'mozallowfullscreen', '' );
					iframe.setAttribute( 'webkitallowfullscreen', '' );
					iframe.setAttribute( 'allow', 'autoplay' );

					iframe.setAttribute( 'data-src', backgroundIframe );

					iframe.style.width  = '100%';
					iframe.style.height = '100%';
					iframe.style.maxHeight = '100%';
					iframe.style.maxWidth = '100%';

					backgroundContent.appendChild( iframe );
				}
			}

			// Start loading preloadable iframes
			let backgroundIframeElement = backgroundContent.querySelector( 'iframe[data-src]' );
			if( backgroundIframeElement ) {

				// Check if this iframe is eligible to be preloaded
				if( this.shouldPreload( background ) && !/autoplay=(1|true|yes)/gi.test( backgroundIframe ) ) {
					if( backgroundIframeElement.getAttribute( 'src' ) !== backgroundIframe ) {
						backgroundIframeElement.setAttribute( 'src', backgroundIframe );
					}
				}

			}

		}

		this.layout( slide );

	}
Called when the given slide is within the configured view
distance. Shows the slide element and loads any content
that is set to load lazily (data-src).

@param {HTMLElement} slide Slide to show