update()

in js/controllers/fragments.js [177:263]
61 lines of code
14 McCabe index (conditional complexity)

	update( index, fragments ) {

		let changedFragments = {
			shown: [],
			hidden: []
		};

		let currentSlide = this.Reveal.getCurrentSlide();
		if( currentSlide && this.Reveal.getConfig().fragments ) {

			fragments = fragments || this.sort( currentSlide.querySelectorAll( '.fragment' ) );

			if( fragments.length ) {

				let maxIndex = 0;

				if( typeof index !== 'number' ) {
					let currentFragment = this.sort( currentSlide.querySelectorAll( '.fragment.visible' ) ).pop();
					if( currentFragment ) {
						index = parseInt( currentFragment.getAttribute( 'data-fragment-index' ) || 0, 10 );
					}
				}

				Array.from( fragments ).forEach( ( el, i ) => {

					if( el.hasAttribute( 'data-fragment-index' ) ) {
						i = parseInt( el.getAttribute( 'data-fragment-index' ), 10 );
					}

					maxIndex = Math.max( maxIndex, i );

					// Visible fragments
					if( i <= index ) {
						let wasVisible = el.classList.contains( 'visible' )
						el.classList.add( 'visible' );
						el.classList.remove( 'current-fragment' );

						if( i === index ) {
							// Announce the fragments one by one to the Screen Reader
							this.Reveal.announceStatus( this.Reveal.getStatusText( el ) );

							el.classList.add( 'current-fragment' );
							this.Reveal.slideContent.startEmbeddedContent( el );
						}

						if( !wasVisible ) {
							changedFragments.shown.push( el )
							this.Reveal.dispatchEvent({
								target: el,
								type: 'visible',
								bubbles: false
							});
						}
					}
					// Hidden fragments
					else {
						let wasVisible = el.classList.contains( 'visible' )
						el.classList.remove( 'visible' );
						el.classList.remove( 'current-fragment' );

						if( wasVisible ) {
							this.Reveal.slideContent.stopEmbeddedContent( el );
							changedFragments.hidden.push( el );
							this.Reveal.dispatchEvent({
								target: el,
								type: 'hidden',
								bubbles: false
							});
						}
					}

				} );

				// Write the current fragment index to the slide <section>.
				// This can be used by end users to apply styles based on
				// the current fragment index.
				index = typeof index === 'number' ? index : -1;
				index = Math.max( Math.min( index, maxIndex ), -1 );
				currentSlide.setAttribute( 'data-fragment', index );

			}

		}

		return changedFragments;

	}