# 0.8 Upgrade guide

The necessary changes depend on what environment you target, and
how you want to provide React.

## Browser - Cljsjs

Using Reagent itself with Cljsjs packages doesn't require changes,
other than making sure you depend on the latest Cljsjs React packages,
if you have direct dependencies to them.

## Browser - node modules

You can use `:npm-deps` and `:install-deps` compiler options to
install the packages automatically.

If `react`, `react-dom` and `create-react-class` are available in `node_modules`
directory, ClojureScript compiler will use these with Reagent. **This
doesn't depend on use of `:npm-deps` option!** `:npm-deps` option is only about
installing the dependencies, if packages are available in `node_modules`
directory, they will be used.

You can use `:process-shim` compiler option to provide `process.env.NODE_ENV`
constant which is used by JS code to enable development and production
builds. ClojureScript compiler will automatically set this constant to
`production` value when using `:advanced` optimizations. This enables
the React production build.

## Browser - loading React from CDNJS or custom Webpack bundle

**TODO: Not tested properly**

If you want to load React.js yourself from external JS file (CDN) or from custom bundle,
it should be possible to override the Cljsjs foreign-libs, while still using externs from Cljsjs packages. To override the foreign-libs, you can provide following compiler option:

```clj
:foreign-libs
 [{:file "empty.js",
   :provides ["react" "react-dom" "create-react-class" "react-dom/server"],
   :requires [],
   :global-exports {react React
                    react-dom ReactDOM
                    create-react-class createReactClass
                    react-dom/server ReactDOMServer}}]
```

You'll also need to create the mentioned `empty.js` file (FIXME: relative to `project.clj`?).

If your bundle provides other libraries, you could extern `:provides` and `:global-exports` (e.g. `prop-types`).

## NodeJS - Cljsjs

Requires https://github.com/clojure/clojurescript/commit/f7d611d87f6ea8a605eae7c0339f30b79a840b49

Reagent should use Cljsjs libraries by default even when running on Node.

## NodeJS - node modules

Install `react`, `react-dom` and `create-react-class` npm packages,
and ClojureScript should automatically use `require` to
load React for Reagent.

## Electron

???

## React-native

https://github.com/drapanjanas/re-natal/issues/128

## Common Problems

### Mismatch with Cljsjs and npm packages

If you have one npm package installed, e.g. `react`, you also need
to provide others (`react-dom` and `create-react-class`), else
Cljsjs packages would be used for these, and packages from different sources
don't work together.