Add a --preact flag to enable a preact-compat build

- react and react-dom are aliased to preact-compat in Webpack config
- Incompatible Babel transforms for React production optimisations are excluded from Babel config

Closes #124

CHANGES.md

@@ -1,5 +1,6 @@
 **Added:**
 
+- Added a `--preact` flag to React app builds to create a [preact-compat](https://github.com/developit/preact-compat)-compatible build. This is a drop-in way to try [preact](https://github.com/developit/preact) with your React app [[#124](https://github.com/insin/nwb/issues/124)]
 - `webpack.compat` now supports `'json-schema': true` to prevent a transitive `json-schema` dependency breaking Webpack builds.
 
 **Changed:**

docs/Commands.md

@@ -66,6 +66,7 @@ react build <entry> [dist_dir] [options]
 
 - `--mount-id` - `id` for the `<div>` the app will render into *[default: app]*
 - `--title` - contents for `<title>` *[default: React App]*
+- `--preact` - create a [preact-compat](https://github.com/developit/preact-compat#usage-with-webpack)-compatible build
 - `--vendor` - create a separate vendor bundle
 
 ### `nwb`
@@ -233,7 +234,6 @@ Builds the component in preparation for publishing to npm.
 
 Passing an argument for `entry` allows you to customise the entry point for the UMD build of your app.
 
-
 - An ES5 build will be created in `lib/`
 - If enabled, UMD builds will be created in `umd/`
 - If enabled, ES6 modules builds will be created in `es6/`

src/commands/build-react-app.js

@@ -27,7 +27,16 @@ let buildConfig = (args) => {
     }
   }
 
-  if (process.env.NODE_ENV === 'production') {
+  if (args.preact) {
+    config.resolve = {
+      alias: {
+        'react': 'preact-compat',
+        'react-dom': 'preact-compat'
+      }
+    }
+  }
+
+  if (process.env.NODE_ENV === 'production' && !args.preact) {
     config.loaders = {
       babel: {
         query: {

src/commands/build-react.js

@@ -38,7 +38,16 @@ let buildConfig = (args) => {
     }
   }
 
-  if (process.env.NODE_ENV === 'production') {
+  if (args.preact) {
+    config.resolve = {
+      alias: {
+        'react': 'preact-compat',
+        'react-dom': 'preact-compat'
+      }
+    }
+  }
+
+  if (process.env.NODE_ENV === 'production' && !args.preact) {
     config.loaders.babel.query.optional = [
       'optimisation.react.inlineElements',
       'optimisation.react.constantElements'