Code blocks

Markdown already supports code samples both inline (using single backticks like `some code here`) and in blocks. Infusion will syntax highlight HTML, CSS, and JavaScript if you provide the correct language in the formulation of the block.

So, this…


```html
<button aria-pressed="false">toggle me</button>
```

… will result in this:

<button aria-pressed="false">toggle me</button>

Note that the syntax highlighting uses a greyscale theme. Infusion is careful not to use color as part of its own design, because these colors may clash with those of the design being illustrated and discussed.

Annotated code

Infusion offers the ability to highlight and annotate specific parts of your code examples using the code shortcode. Take an accessible dialog. You may wish to point out key attributes that make that dialog support assistive technologies:


<div role="dialog" aria-labelledby="dialog-heading">
  <button aria-label="close">x</button>
  <h2 id="dialog-heading">Confirmation</h2>
  <p>Press <strong>Okay</strong> to confirm or <strong>Cancel</strong></p>
  <button>Okay</button>
  <button>Cancel</button>
</div>

You mark out the highlighted areas using triple square brackets like so:


{{<code>}}
<div [[[role="dialog"]]] [[[aria-labelledby="dialog-heading"]]]>
  <button [[[aria-label="close"]]]>x</button>
  <h2 [[[id="dialog-heading"]]]>Confirmation</h2>
  <p>Press Okay to confirm or Cancel</p>
  <button>Okay</button>
  <button>Cancel</button>
</div>
{{</code>}}

Better still, if you include numbered="true", each highlight is enumerated so you can reference it directly in the ensuing text. If you follow the shortcode directly with an ordered list, the styles match:


<div role="dialog" aria-labelledby="dialog-heading">
  <button aria-label="close">x</button>
  <h2 id="dialog-heading">Confirmation</h2>
  <p>Press <strong>Okay</strong> to confirm or <strong>Cancel</strong></p>
  <button>Okay</button>
  <button>Cancel</button>
</div>

The dialog is only announced as a dialog if it takes the dialog ARIA role
The aria-labelledby relationship attribute makes the element carrying the id it points to its label
The close button uses aria-label to provide the text label “close”, overriding the text content
The heading is used as the dialog’s label. The aria-labelledby attribute points to its id

You just include numbered="true" on the opening shortcode tag:


{{<code numbered="true">}}
<div [[[role="dialog"]]] [[[aria-labelledby="dialog-heading"]]]>
  <button [[[aria-label="close"]]]>x</button>
  <h2 [[[id="dialog-heading"]]]>Confirmation</h2>
  <p>Press Okay to confirm or Cancel</p>
  <button>Okay</button>
  <button>Cancel</button>
</div>
{{</code>}}

1. The dialog is only announced as a dialog if it takes the `dialog` ARIA role
2. The `aria-labelledby` relationship attribute makes the element carrying the `id` it points to its label
3. The close button uses `aria-label` to provide the text label "close", overriding the text content
4. The heading is used as the dialog's label. The `aria-labelledby` attribute points to its `id`

JavaScript example


/* Enable scrolling by keyboard of code samples */
(function () {
  var codeBlocks = document.querySelectorAll('pre, .code-annotated');

  Array.prototype.forEach.call(codeBlocks, function (block) {
    if (block.querySelector('code')) {
      block.setAttribute('role', 'region');
      block.setAttribute('aria-label', 'code sample');
      if (block.scrollWidth > block.clientWidth) {
        block.setAttribute('tabindex', '0');
      }
    }
  });
}());

The region role announces the block as a region
The aria-label describes the kind of content to be expected in the region