Webpack loader fails when importing .css in react_on_rails app? - reactjs

Question

I am trying to use react-datetime on my react-on-rails app. To make the datetime work out of the box, I need to import the CSS mentioned on their GH page.
On my app, I copy/paste the CSS into a file I named DateTime.css:
...
import DateTime from 'react-datetime';
import '../../schedules/stylesheets/DateTime.css';
...
export default class AddDate extends React.Component {
But it gives me this error:
VM45976:1 Uncaught Error: Module parse failed: /Users/some/path/to/my/project/App/components/schedules/stylesheets/DateTime.css Unexpected token (1:0)
You may need an appropriate loader to handle this file type.
| .rdt {
| position: relative;
| }
It seems like the CSS loader is not working. I tried this on pure react app (create-react-app) and it worked. It broke when I did it inside react_on_rails.
This is my webpack config atm (standard out-of-the-box react_on_rails):
const webpack = require('webpack');
const { resolve } = require('path');
const ManifestPlugin = require('webpack-manifest-plugin');
const webpackConfigLoader = require('react-on-rails/webpackConfigLoader');
const configPath = resolve('..', 'config');
const { devBuild, manifest, webpackOutputPath, webpackPublicOutputDir } =
webpackConfigLoader(configPath);
const config = {
context: resolve(__dirname),
entry: {
'webpack-bundle': [
'es5-shim/es5-shim',
'es5-shim/es5-sham',
'babel-polyfill',
'./app/bundles/App/startup/registration',
],
},
output: {
// Name comes from the entry section.
filename: '[name]-[hash].js',
// Leading slash is necessary
publicPath: `/${webpackPublicOutputDir}`,
path: webpackOutputPath,
},
resolve: {
extensions: ['.js', '.jsx'],
},
plugins: [
new webpack.EnvironmentPlugin({
NODE_ENV: 'development', // use 'development' unless process.env.NODE_ENV is defined
DEBUG: false,
}),
new ManifestPlugin({ fileName: manifest, writeToFileEmit: true }),
],
module: {
rules: [
{
test: require.resolve('react'),
use: {
loader: 'imports-loader',
options: {
shim: 'es5-shim/es5-shim',
sham: 'es5-shim/es5-sham',
},
},
},
{
test: /\.jsx?$/,
use: 'babel-loader',
exclude: /node_modules/,
},
{
test: /\.css$/,
use: 'css-loader',
exclude: /node_modules/,
},
],
],
},
};
module.exports = config;
if (devBuild) {
console.log('Webpack dev build for Rails'); // eslint-disable-line no-console
module.exports.devtool = 'eval-source-map';
} else {
console.log('Webpack production build for Rails'); // eslint-disable-line no-console
}
I am very new in webpack, and not sure how to I can add loaders to make it work, how can I apply the DateTime.css file that I have to be applied to react-datetime?
EDIT: added css-loader (also updated the webpack above). It is no longer complaining that I don't have the correct loader, but the CSS does not work.
{
test: /\.jsx?$/,
use: 'babel-loader',
exclude: /node_modules/,
},
{
test: /\.css$/,
use: 'css-loader',
exclude: /node_modules/,
},
],

Answer 1

There are 2 conceptually different ways to approach this.
1. Using CSS modules.
This way your CSS will end up bundled with your JS and as soon as webpack loads that JS module/bundle it will automatically append CSS style element into the head.
In my project I have this rule to do exactly that (note that we use both css-loader and style-loader):
{
test: /\.css$/,
use: ['style-loader', {
loader: 'css-loader',
options: {
modules: true,
localIdentName: '[path][name]__[local]--[hash:base64:5]'
}
}]
}
More on css-loader modules at this link.
2. Using ExtractTextPlugin. This way all your CSS will be extracted into a separate file. The configuration requires 2 things: a plugin and loaders configuration created by the plugin:
const ExtractTextPlugin = require('extract-text-webpack-plugin');
// Add this to your webpack plugins array
new ExtractTextPlugin('styles.css')
And add this to your rules:
{
test: /\.css$/,
exclude: /node_modules/,
use: ExtractTextPlugin.extract({
fallback: 'style-loader',
use: ['css-loader']
})
}
This will create one single styles.css file and put all CSS you import from JS into that file.