How to webpack React.js using uglify version - reactjs

Question

I would like to webpack my React.js app using uglify version
webpack.config.js
module.exports = {
entry: './_react/index',
output: {
path: './dist/public/app',
filename: 'bundle.min.js'
},
devtool: 'source-map',
devServer: {
contentBase: __dirname
},
module: {
loaders: [{
test: /\.js?$/,
exclude: /(node_modules|bower_components)/,
loader: ['babel-loader'],
query: {
presets: ['es2015', 'react']
}
}]
}
}
Terminal
webpack -p
After previewing on the web browser, I got this error
Please guide, thanks

Answer 1

As jmargolisvt said, you need to set the NODE_ENV.
Try updating your webpack.config.js with the following:
plugins: [
new webpack.DefinePlugin({
'process.env': {
'NODE_ENV': JSON.stringify('production')
}
})
],
Or in your current config as:
module.exports = {
entry: './_react/index',
output: {
path: './dist/public/app',
filename: 'bundle.min.js'
},
devtool: 'source-map',
devServer: {
contentBase: __dirname
},
module: {
loaders: [{
test: /\.js?$/,
exclude: /(node_modules|bower_components)/,
loader: ['babel-loader'],
query: {
presets: ['es2015', 'react']
}
}]
}
plugins: [
new webpack.DefinePlugin({
'process.env': {
'NODE_ENV': JSON.stringify('production')
}
})
],
}
Make sure to use JSON.stringify to insert a string and not the variable production

Answer 2

You need to set the NODE_ENV to production. From the React site:
Note: by default, React will be in development mode. To use React in production mode, set the environment variable NODE_ENV to production (using envify or webpack's DefinePlugin).