cupper-hugo-theme/content/patterns/coding/code-blocks.md

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title = "Code blocks"
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weight = 1
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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…
{{<codeBlock>}}
```html
&lt;button aria-pressed="false">toggle me&lt;/button>
```
{{</codeBlock>}}
&hellip; will result in this:
```html
<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.
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{{% note %}}
To preserve the wrapping inside code blocks, horizontal scrolling is implemented. To make sure scrolling is keyboard accessible, code blocks are focusable. An `aria-label` is provided to identify the code block to screen reader users.
{{% /note %}}
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## Annotated code
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**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:
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{{<html>}}
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<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>
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{{</html>}}
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You mark out the highlighted areas using triple square brackets like so:
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{{<codeBlock>}}
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&#x7b;{&lt;code>}}
&lt;div [[[role="dialog"]]] [[[aria-labelledby="dialog-heading"]]]>
&lt;button [[[aria-label="close"]]]>x&lt;/button>
&lt;h2 [[[id="dialog-heading"]]]>Confirmation&lt;/h2>
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&lt;p>Press <strong>Okay</strong> to confirm or <strong>Cancel</strong>&lt;/p>
&lt;button>Okay&lt;/button>
&lt;button>Cancel&lt;/button>
&lt;/div>
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&#x7b;{&lt;/code>}}
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{{</codeBlock>}}
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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:
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{{<code numbered="true">}}
<div [[[role="dialog"]]] [[[aria-labelledby="dialog-heading"]]]>
<button [[[aria-label="close"]]]>x</button>
<h2 [[[id="dialog-heading"]]]>Confirmation</h2>
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<p>Press <strong>Okay</strong> to confirm or <strong>Cancel</strong></p>
<button>Okay</button>
<button>Cancel</button>
</div>
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{{</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`
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You just include `numbered="true"` on the opening shortcode tag:
{{<codeBlock>}}
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&#x7b;{&lt;code numbered="true">}}
&lt;div [[[role="dialog"]]] [[[aria-labelledby="dialog-heading"]]]>
&lt;button [[[aria-label="close"]]]>x&lt;/button>
&lt;h2 [[[id="dialog-heading"]]]>Confirmation&lt;/h2>
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&lt;p>Press <strong>Okay</strong> to confirm or <strong>Cancel</strong>&lt;/p>
&lt;button>Okay&lt;/button>
&lt;button>Cancel&lt;/button>
&lt;/div>
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&#x7b;{&lt;/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`
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{{</codeBlock>}}
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### JavaScript example
{{<code numbered="true">}}
/* 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');
}
}
});
}());
{{</code>}}
1. The `region` role announces the block as a region
2. The `aria-label` describes the kind of content to be expected in the region
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{{% note %}}
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As you may have noticed, using specified highlights with the `code` shortcode sacrifices syntax highlighting. If you want syntax highlighting you must use the markdown triple back-tick syntax and annotation is not available.
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{{% /note %}}