MiniCssExtractPlugin is garbling and obfuscating my class names - css

Question

I am using MiniCssExtractPlugin in my typescript and webpack project.
My webpack config for the MiniCssExtractPlugin looks like
const path = require("path");
const HtmlWebpackPlugin = require("html-webpack-plugin");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
module.exports = {
entry: './src/index.tsx',
mode: "development",
output: {
path: path.resolve(__dirname, "build"),
filename: 'bundle.js'
},
module: {
rules: [
{
test: /\.tsx?$/,
loader: "awesome-typescript-loader"
},
{
enforce: "pre",
test: /\.js$/,
loader: "source-map-loader"
},
{
test: /\.scss$/,
use: [
MiniCssExtractPlugin.loader,
{
loader: "css-loader",
options: {
modules: true,
sourceMap: true,
importLoader: 2
}
},
"sass-loader"
]
}
]
},
plugins: [
new HtmlWebpackPlugin({
template: "./index.html"
}),
new MiniCssExtractPlugin({
filename: "foo.css",
chunkFilename: "[id].css"
})],
devtool: "source-map",
resolve: {
extensions: [".js", ".ts", ".tsx"]
}
}
Now the scss file in my project has this fragment
h1 {
border-bottom: 3px solid #880055;
display: inline;
}
.container {
font-size: 1.3rem;
}
.is-completed {
text-decoration: line-through;
color: #00ff00;
}
when my application is run using npm start I can see that the heading H1 has a underline of the color 880055. So this means that my scss file was read correctly.
If I go into chrome developer tools and go into network tab and look for CSS. I can see a foo.css being downloaded. If I look into the content of foo.css
It doesn't have my "is-completed" class. instead I see something like
h1 {
border-bottom: 3px solid #880055;
display: inline; }
.pxcHIyOVHeytUeG27u4TO {
font-size: 1.3rem; }
._1Z5_KVJNKd1X2P3HKM63j {
text-decoration: line-through;
color: #00ff00; }
So element classes like h1 are good, but everything else is garbled. What's going on?

Answer 1

When you set modules: true in your CSS config you are telling the css-loader to use CSS-Modules to scope your class names to a particular file.

Answer 2

You can use the localIndentName query paramater in the css-loader options to specify what you want your generated class (identifier) to look like in development and/or in prod. See example below for what solved this for me.
module.exports = {
module: {
rules: [
{
test: /\.css$/i,
loader: 'css-loader',
options: {
modules: {
localIdentName: '[name]-[local]--[hash:base64:5]',
},
},
},
],
},
};
If I were to use the configuration in the example above and the name of the component that I was rendering was called HelloWorld and a class used in that component was .container, if I were to run my app (dev or prod) and inspect the element in the devtools the class on my HelloWorld component appear as follows:
<div class="HelloWorld-container--16ABh"> Hello World </div>
You can play around with what you set as your localIdentName and how many characters of the hash you show.
See the documentation for the localIdentName query param here: https://github.com/webpack-contrib/css-loader#localidentname