nfreear/accessibility.wai-aria.ajax-loading-demo.js.html

## accessibility.wai-aria.ajax-loading-demo.js.html
<!doctype html><html lang="en"><meta charset="utf-8">

<title> "More" button loading demo (WAI-ARIA) </title>

<style>
  body { margin: 1rem auto; max-width: 35rem; padding: .5rem; }
  main { font: 1rem/1.5 sans-serif; position: relative; }

  /* Accessibility / Usability - visually indicate new content.

    @TODO: customise, animate - https://code-boxx.com/glowing-text-pure-css/ .. etc.
  */
  .glow {
    box-shadow: 0 0 2rem .5rem teal;
    text-shadow: 0 0 .5rem #fff700;
    transition: all 2s;
  }

  .loading {
    cursor: wait;
  }

  .loading .morebtn_wrapper,
  .loading #more-button {
    border: none;
    outline: none;
    max-height: 1px;
    max-width: 1px;
    overflow: hidden !important;
    transition: all 3s;
  }

  .loading-complete .morebtn_wrapper {
    display: none;
  }

  #more-status {
    position: absolute;
    left: 0;
    top: 50%;
    height: 100px;
    width: 100%;
    margin-top: -50px; /* account for padding and border if not using box-sizing: border-box; */
  }

  /* Accessibility / Usability - visual loading indicator.
  */
  #more-status > * {
    background-color: #f8f8f8;
    background-image: url(https://upload.wikimedia.org/wikipedia/commons/7/7a/Ajax_loader_metal_512.gif);
    background-position: center bottom;
    background-repeat: no-repeat;
    background-size: contain;
    display: block;
    font-size: large;
    margin: 0 auto;
    max-width: 9rem;
    text-align: center;
    height: 12rem;
    padding: .5rem;
  }

  #grid-container > * {
    border: 1px solid #bbb;
    margin: 1rem 0;
    padding: .7rem;
  }

  /* Copy styles.
  */
  #grid-container > .morebtn_wrapper {
    border: none;

    padding: 50px 0 100px;
    text-align: center;
  }

  .morebtn {
    border: 2px solid #808080;
    display: inline-block;
    text-decoration: none;
    text-align: center;
    font-weight: 700;
    font-size: 20px;
    line-height: 24px;
    color: #808080;
    padding: 18px 24px;
    min-width: 242px;
    position: relative;
    text-transform: uppercase;
    border-radius: 60px;
    -moz-border-radius: 60px;
    -webkit-border-radius: 60px;
    -ms-border-radius: 60px;
    position: relative;

    background: white;
    cursor: pointer;
  }

  .morebtn::after {
    content: '';
    position: absolute;
    display: block;
    background-image: url(https://iet.double.systems//images/svg/more.svg);
    background-repeat: no-repeat;
    background-position: center center;
    background-size: cover;
    display: inline-block;
    vertical-align: middle;
    width: 18px;
    height: 18px;
    left: 50%;
    margin-left: -9px;
    bottom: -27px;
  }
</style>


<h1> "More" button loading demo (WAI-ARIA) </h1>

<p> Please VIEW SOURCE to look at the HTML markup and Javascript. </p>

<p> Important — <a href="https://w3.org/TR/wai-aria-practices/#no_aria_better_bad_aria">No ARIA is better than Bad ARIA</a>!</p>


<!-- Accessibility - use a "main" landmark role. -->
<main role="main">

  <!-- Screen reader accessibility - WAI-ARIA live region - status. -->
  <div id="more-status" role="status" aria-live="polite"></div>

  <!-- Screen reader accessibility - WAI-ARIA live region - grid-container. -->
  <div id="grid-container" role="region" aria-live="polite" aria-label="Articles">

    <article tabindex="-1"> <h2> Grid article 1. </h2> </article>

    <article tabindex="-1"> <h2> Grid article 2. </h2> </article>

    <article tabindex="-1"> <h2> Grid article 3. </h2> </article>

    <article tabindex="-1"> <h2> Grid article 4. </h2> </article>

    <!-- <article> <h2> Grid article 5. </h2> </article> -->


    <!-- Accessibility - use a "form" role and an "aria-label". -->
    <div class="morebtn_wrapper" role="form" aria-label="Load more content">
      <!--
        Keyboard accessibility.

        Make this a <button> so it behaves well with 'SPACE-BAR' as well as 'ENTER' keys!
      -->
      <button id="more-button" class="morebtn" aria-label="Load more content" type="button">More</button>
    </div>

  </div>

</main>


<script>
// Mockup an Ajax request.
const DELAY_MS = 4000;
const ITEMS = [ 5, 6, 7, 8 /*, 9, 10 */ ]; // Clunk!
const FIRST_IDX = ITEMS[0];

const BODY = document.body;
const CONTAINER = document.querySelector('#grid-container');
const MORE_STATUS = document.querySelector('#more-status');
const MORE_BUTTON = document.querySelector('#more-button');

// Accessibility - use the "click" event with a "real" <button>!
MORE_BUTTON.addEventListener('click', ev => {
  ev.preventDefault();

  console.warn('"More" button clicked - Loading content', ev);

  // Accessibility - visiual "loading" indicator(s)
  BODY.classList.add('loading');
  BODY.classList.add('more-button-clicked');

  // Accessibility - non-visual "loading" indicator".
  MORE_STATUS.innerHTML = '<div>Loading content</div>';

  // Mockup an Ajax request.
  setTimeout(() => {
    BODY.classList.remove('loading');
    BODY.classList.add('loading-complete');

    ITEMS.forEach(index => {
      const ELEM = document.createElement('article');

      ELEM.innerHTML = `<h2> Grid article ${index}. </h2>`;
      ELEM.id = `grid-item-${index}`;
      ELEM.setAttribute('tabindex', '-1');

      CONTAINER.appendChild(ELEM);
    });

    // Tidy up!
    MORE_STATUS.textContent = '';

    const FIRST_LOADED = document.querySelector(`#grid-item-${FIRST_IDX}`);

    // Keyboard accessibility - set focus.
    FIRST_LOADED.focus();

    FIRST_LOADED.scrollIntoView({ behavior: 'smooth', block: 'start' });

    // Accessibility / usability - visually indicate new content.
    FIRST_LOADED.classList.add('glow');
    setTimeout(() => FIRST_LOADED.classList.remove('glow'), DELAY_MS);

    console.warn('Loading content - completed!');
  },
  DELAY_MS);
});
</script>


<pre>


What this page demonstrates:

 1. The "More" button is keyboard accessible with the SPACE-BAR and ENTER keys;
 2. Screen reader users are informed as the page starts to load more content;
 3. Screen reader users are read the new content when it arrives;
 4. Keyboard focus is set on the first new article;
 5. The page is scrolled to the first new article;
 6. The first new article is visually highlighted;

Nick Freear, 20-April-2021.

</pre>
	<!doctype html><html lang="en"><meta charset="utf-8">

	<title> "More" button loading demo (WAI-ARIA) </title>

	<style>
	body { margin: 1rem auto; max-width: 35rem; padding: .5rem; }
	main { font: 1rem/1.5 sans-serif; position: relative; }

	/* Accessibility / Usability - visually indicate new content.

	@TODO: customise, animate - https://code-boxx.com/glowing-text-pure-css/ .. etc.
	*/
	.glow {
	box-shadow: 0 0 2rem .5rem teal;
	text-shadow: 0 0 .5rem #fff700;
	transition: all 2s;
	}

	.loading {
	cursor: wait;
	}

	.loading .morebtn_wrapper,
	.loading #more-button {
	border: none;
	outline: none;
	max-height: 1px;
	max-width: 1px;
	overflow: hidden !important;
	transition: all 3s;
	}

	.loading-complete .morebtn_wrapper {
	display: none;
	}

	#more-status {
	position: absolute;
	left: 0;
	top: 50%;
	height: 100px;
	width: 100%;
	margin-top: -50px; /* account for padding and border if not using box-sizing: border-box; */
	}

	/* Accessibility / Usability - visual loading indicator.
	*/
	#more-status > * {
	background-color: #f8f8f8;
	background-image: url(https://upload.wikimedia.org/wikipedia/commons/7/7a/Ajax_loader_metal_512.gif);
	background-position: center bottom;
	background-repeat: no-repeat;
	background-size: contain;
	display: block;
	font-size: large;
	margin: 0 auto;
	max-width: 9rem;
	text-align: center;
	height: 12rem;
	padding: .5rem;
	}

	#grid-container > * {
	border: 1px solid #bbb;
	margin: 1rem 0;
	padding: .7rem;
	}

	/* Copy styles.
	*/
	#grid-container > .morebtn_wrapper {
	border: none;

	padding: 50px 0 100px;
	text-align: center;
	}

	.morebtn {
	border: 2px solid #808080;
	display: inline-block;
	text-decoration: none;
	text-align: center;
	font-weight: 700;
	font-size: 20px;
	line-height: 24px;
	color: #808080;
	padding: 18px 24px;
	min-width: 242px;
	position: relative;
	text-transform: uppercase;
	border-radius: 60px;
	-moz-border-radius: 60px;
	-webkit-border-radius: 60px;
	-ms-border-radius: 60px;
	position: relative;

	background: white;
	cursor: pointer;
	}

	.morebtn::after {
	content: '';
	position: absolute;
	display: block;
	background-image: url(https://iet.double.systems//images/svg/more.svg);
	background-repeat: no-repeat;
	background-position: center center;
	background-size: cover;
	display: inline-block;
	vertical-align: middle;
	width: 18px;
	height: 18px;
	left: 50%;
	margin-left: -9px;
	bottom: -27px;
	}
	</style>


	<h1> "More" button loading demo (WAI-ARIA) </h1>

	<p> Please VIEW SOURCE to look at the HTML markup and Javascript. </p>

	<p> Important — <a href="https://w3.org/TR/wai-aria-practices/#no_aria_better_bad_aria">No ARIA is better than Bad ARIA</a>!</p>


	<!-- Accessibility - use a "main" landmark role. -->
	<main role="main">

	<!-- Screen reader accessibility - WAI-ARIA live region - status. -->
	<div id="more-status" role="status" aria-live="polite"></div>

	<!-- Screen reader accessibility - WAI-ARIA live region - grid-container. -->
	<div id="grid-container" role="region" aria-live="polite" aria-label="Articles">

	<article tabindex="-1"> <h2> Grid article 1. </h2> </article>

	<article tabindex="-1"> <h2> Grid article 2. </h2> </article>

	<article tabindex="-1"> <h2> Grid article 3. </h2> </article>

	<article tabindex="-1"> <h2> Grid article 4. </h2> </article>

	<!-- <article> <h2> Grid article 5. </h2> </article> -->


	<!-- Accessibility - use a "form" role and an "aria-label". -->
	<div class="morebtn_wrapper" role="form" aria-label="Load more content">
	<!--
	Keyboard accessibility.

	Make this a <button> so it behaves well with 'SPACE-BAR' as well as 'ENTER' keys!
	-->
	<button id="more-button" class="morebtn" aria-label="Load more content" type="button">More</button>
	</div>

	</div>

	</main>



	<script>
	// Mockup an Ajax request.
	const DELAY_MS = 4000;
	const ITEMS = [ 5, 6, 7, 8 /, 9, 10 / ]; // Clunk!
	const FIRST_IDX = ITEMS[0];

	const BODY = document.body;
	const CONTAINER = document.querySelector('#grid-container');
	const MORE_STATUS = document.querySelector('#more-status');
	const MORE_BUTTON = document.querySelector('#more-button');

	// Accessibility - use the "click" event with a "real" <button>!
	MORE_BUTTON.addEventListener('click', ev => {
	ev.preventDefault();

	console.warn('"More" button clicked - Loading content', ev);

	// Accessibility - visiual "loading" indicator(s)
	BODY.classList.add('loading');
	BODY.classList.add('more-button-clicked');

	// Accessibility - non-visual "loading" indicator".
	MORE_STATUS.innerHTML = '<div>Loading content</div>';

	// Mockup an Ajax request.
	setTimeout(() => {
	BODY.classList.remove('loading');
	BODY.classList.add('loading-complete');

	ITEMS.forEach(index => {
	const ELEM = document.createElement('article');

	ELEM.innerHTML = `<h2> Grid article ${index}. </h2>`;
	ELEM.id = `grid-item-${index}`;
	ELEM.setAttribute('tabindex', '-1');

	CONTAINER.appendChild(ELEM);
	});

	// Tidy up!
	MORE_STATUS.textContent = '';

	const FIRST_LOADED = document.querySelector(`#grid-item-${FIRST_IDX}`);

	// Keyboard accessibility - set focus.
	FIRST_LOADED.focus();

	FIRST_LOADED.scrollIntoView({ behavior: 'smooth', block: 'start' });

	// Accessibility / usability - visually indicate new content.
	FIRST_LOADED.classList.add('glow');
	setTimeout(() => FIRST_LOADED.classList.remove('glow'), DELAY_MS);

	console.warn('Loading content - completed!');
	},
	DELAY_MS);
	});
	</script>



	<pre>


	What this page demonstrates:

	1. The "More" button is keyboard accessible with the SPACE-BAR and ENTER keys;
	2. Screen reader users are informed as the page starts to load more content;
	3. Screen reader users are read the new content when it arrives;
	4. Keyboard focus is set on the first new article;
	5. The page is scrolled to the first new article;
	6. The first new article is visually highlighted;

	Nick Freear, 20-April-2021.

	</pre>