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Merge pull request #346 from jmlsf/patch-1 

Improve UsingRefs.md
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docs/FAQ/UsingRefs.md
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@ -28,11 +28,11 @@ We'll start with a code fragment, because it is worth a 1000 words:
```
Notes:
1. That's a Form-2 component. That allows us to retain state outside of the renderer `fn`.
2. We capture state in `!video`. The state we capture is a reference to a video component.
2. `!video` is a `clojure.core/atom` and not a `reaagent.core/atom`
4. On the `:video` component there's a `:ref` callback function which establishes the state in `!video`
5. Thereafter, `@!video` is used with the `:button's` `:on-click` to manipulate the `video`
1. This example uses a Form-2 component, which allows us to retain state outside of the renderer `fn`. The same technique would work with a Form-3 component.
2. We capture state in `!video`. In this example, the state we capture is a reference to a [video HTML element](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/video).
2. `!video` is a `clojure.core/atom` and not a `reaagent.core/atom`. We don't use a normal atom because refs never change during the lifecycle of a component and if we used a reagent atom, it would cause an unnecessary re-render when the ref callback mutates the atom.
4. On the `:video` component there's a `:ref` callback function which establishes the state in `!video`. You can attach a ref callback to any of the Hiccup elements.
5. Thereafter, `@!video` is used with the `:button's` `:on-click` to manipulate the `video` DOM methods.
5. For full notes [read Paulus' blog post](https://presumably.de/reagent-mysteries-part-3-manipulating-the-dom.html)
6. For more background on callback refs, see [React's documentation](https://facebook.github.io/react/docs/more-about-refs.html)