Zhao Yi Zhao Yi - 3 months ago 174
Node.js Question

Why webpack gives an error for about NODE_ENV?

I am using webpack+react+redux on a web application. And I am using

webpack-dev-server
to launch dev web server. When I access my application on a browser, it gives below error messages on the console:

Warning: It looks like you're using a minified copy of the development build of React. When deploying React apps to production, make sure to use the production build which skips development warnings and is faster.

You are currently using minified code outside of NODE_ENV === 'production'. This means that you are running a slower development build of Redux. You can use loose-envify to ensure you have the correct code for your production build.


Below is my webpack.config.js file. I didn't specify production mode, why webpack gives me such warning message? And how can I get rid of it?

const webpack = require('webpack');
const path = require('path');
const NpmInstallPlugin = require('npm-install-webpack-plugin');
const WebpackShellPlugin = require('webpack-shell-plugin');
var CompressionPlugin = require("compression-webpack-plugin");

const PATHS = {
react: path.join(__dirname, 'node_modules/react/dist/react.min.js'),
app: path.join(__dirname, 'src'),
build: path.join(__dirname, './dist')
};

module.exports = {
entry: {
app: './app/index.jsx',
android: './app/utils/platform_android.js',
ios: './app/utils/platform_ios.js',
web: './app/utils/platform_web.js',
vendor: [
'axios',
'react',
'react-dom',
'react-redux',
'react-router',
'react-router-redux',
'redux',
'redux-thunk',
'react-alert',
'sha1',
'moment',
'nuka-carousel',
'react-cookie',
'material-ui',
'react-spinkit',
'react-tap-event-plugin',
'react-tappable',
],
},
output: {
path: PATHS.build,
filename: '[name].bundle.js',
},
watch: true,
devtool: 'source-map',
relativeUrls: true,
resolve: {
extensions: ['', '.js', '.jsx', '.css', '.less'],
modulesDirectories: ['node_modules'],
alias: {
normalize_css: __dirname + '/node_modules/normalize.css/normalize.css',
}
},
module: {
preLoaders: [

{
test: /\.js$/,
loader: "source-map-loader"
},
// {
// test: /\.js$/,
// exclude: /node_modules/,
// loader: 'jshint-loader'

// }
],
loaders: [

{
test: /\.html$/,
loader: 'file?name=[name].[ext]',
},
{
test: /\.jsx?$/,
exclude: /node_modules/,
loader: 'babel-loader?presets=es2015',
},
{
test: /\.less$/,
loader: "style!css!less",
},
{test: /\.css$/, loader: 'style-loader!css-loader'},
{test: /\.png$/, loader: "url-loader?limit=100000"},

{
test: /\.js$/,
exclude: /node_modules/,
loaders: ['babel-loader?presets=es2015']
},
{
test: /\.svg$/,
loader: 'svg-sprite',
include: /public\/icons/
}
]
},
plugins: [
new webpack.optimize.UglifyJsPlugin({
compress: {
warnings: false,
},
output: {
comments: false,
},
}),
new NpmInstallPlugin({
save: true // --save
}),

new CompressionPlugin({
asset: "[path].gz[query]",
algorithm: "gzip",
test: /\.js$|\.html$/,
threshold: 10240,
minRatio: 0.8
}),
new webpack.optimize.CommonsChunkPlugin(/* chunkName= */["vendor"], /* filename= */"[name].bundle.js", Infinity),
],
devServer: {
colors: true,
contentBase: __dirname,
historyApiFallback: true,
hot: true,
inline: true,
port: 9093,
progress: true,
stats: {
cached: false
}
}
}


EDIT1:

I removed this line:

react: path.join(__dirname, 'node_modules/react/dist/react.min.js'),


Then updated the NODE_ENV to development as below:

new webpack.DefinePlugin({
"process.env": {
NODE_ENV: JSON.stringify("development")
}
})


Then I still got the same warning.

warning.js:14You are currently using minified code outside of NODE_ENV === 'production'. This means that you are running a slower development build of Redux. You can use loose-envify (https://github.com/zertosh/loose-envify) for browserify or DefinePlugin for webpack (http://stackoverflow.com/questions/30030031) to ensure you have the correct code for your production build.

Answer

The warning you get now is because you are letting Webpack minify your build, but you are still setting NODE_ENV to development.

If you use UglifyJsPlugin you should always set NODE_ENV to production. If you're not building for production, remove UglifyJsPlugin to not get any warnings.

Webpack, React and Redux try to give you some best practice hints here. In development mode (NODE_ENV not set to production), they all give more warnings and have lower performance. When you minify them they assume you're running a production build. For production builds, they really expect NODE_ENV to be set correctly.

So in short:

  • Production builds: set NODE_ENV to production and use UglifyJsPlugin.
  • Dev builds: set NODE_ENV to development and don't use any minification plugins.
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