Initial AD port

themes/after-dark/docs/content/feature/jit-requests.md

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+title = "JIT Requests"
+description = "Maximize resources while minimizing external requests."
+categories = ["experience"]
+tags = ["performance", "styles", "javascript"]
+features = ["related content", "snippets", "code highlighter"]
+[[copyright]]
+  owner = "Josh Habdas"
+  date = "2019"
+  license = "agpl-3.0-or-later"
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+
+After Dark makes <abbr title="Just-In-Time">JIT</abbr> requests for some external assets to cut down on resource consumption and increase page performance.
+
+Take the [Code Highlighter](../code-highlighter) stylesheet for example:
+
+{{< highlight css >}}
+{{< include "themes/after-dark/static/css/syntax.css" >}}
+{{< /highlight >}}
+
+The stylesheet code shown above is itself highlighted using a JIT request. Confirm by viewing the network requests for this page and observe the `fetch` request for the `syntax.css` file as depicted here:
+
+```sh
+jit-requests (document)
+├── lazysizes.min.js (fetch)
+├── syntax.css (fetch)
+```
+
+Using [Fetch Injection](../fetch-injection) a JIT request is issued to begin downloading the highlighter stylesheet on-the-fly in parallel with other resources and the base layout takes care to ensure the CSS is only requested on pages that need it.
+
+Create your own JIT requests using [Custom Layout](../custom-layouts) and [Fetch Injection](../fetch-injection).