Webpack 4 - Minify CSS that was compiled from SCSS - css

Question

Developing a wordpress site and using webpack to bundle assets.
I have a setup where I'm compiling SCSS to CSS among other things. I want to minify the output CSS and remove comments. I tried to add optimize-css-assets-webpack-plugin and configure it as example suggests, but it doesn't work (no errors)...
So how can I modify this webpack config so that output is (1) stripped of comments and (2) minified?
webpack.config.js:
const path = require("path");
const config = require('./config.js');
const BrowserSyncPlugin = require('browser-sync-webpack-plugin');
const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
module.exports = {
mode: 'production',
entry: ["./src/app.js", "./src/scss/style.scss"],
output: {
path: path.resolve(__dirname, "wp-content/themes/ezdigital"),
filename: "js/[name].js"
},
module: {
rules: [
{
test: /\.scss$/,
use: [
{
loader: "file-loader",
options: {
name: "[name].css"
}
},
{
loader: "extract-loader"
},
{
loader: "css-loader?-url"
},
{
loader: "postcss-loader"
},
{
loader: "sass-loader"
}
]
},
{
test: /\.js$/,
exclude: /(node_modules)/,
use: {
loader: "babel-loader",
options: {
presets: ["env"]
}
}
},
{
test: /\.(png|svg|jpg|gif)$/,
use: ["file-loader"]
}
]
},
//remove comments from JS files
optimization: {
minimizer: [
new UglifyJsPlugin({
uglifyOptions: {
output: {
comments: false,
},
},
}),
],
},
plugins: [
new BrowserSyncPlugin( {
proxy: config.url,
files: [
'**/*.php'
],
reloadDelay: 0
}
)
]
};
additional postss.config.js:
module.exports = {
plugins: {
'autoprefixer': {}
}
}
Package.json:
{
"name": "EZTheme",
"version": "1.0.0",
"description": "EZ Theme",
"main": "index.js",
"scripts": {
"test": "test",
"build": "webpack",
"start": "webpack --watch",
"serve": "webpack-dev-server --open"
},
"repository": {
"type": "git",
"url": ""
},
"author": "",
"license": "ISC",
"bugs": {
"url": ""
},
"homepage": ""
"devDependencies": {
"#fortawesome/fontawesome-free": "^5.6.3",
"autoprefixer": "^9.3.1",
"babel-core": "^6.26.3",
"babel-loader": "^7.1.5",
"babel-preset-env": "^1.7.0",
"browser-sync-webpack-plugin": "^2.2.2",
"css-loader": "^1.0.1",
"exports-loader": "^0.7.0",
"extract-loader": "^3.1.0",
"extract-text-webpack-plugin": "^4.0.0-alpha.0",
"file-loader": "^2.0.0",
"jquery": "^3.3.1",
"node-sass": "^4.11.0",
"optimize-css-assets-webpack-plugin": "^5.0.1",
"popper.js": "^1.14.6",
"postcss-cli": "^6.0.1",
"postcss-loader": "^3.0.0",
"sass-loader": "^7.1.0",
"style-loader": "^0.23.1",
"uglifyjs-webpack-plugin": "^2.1.1",
"webpack": "^4.28.2",
"webpack-cli": "^3.1.2",
"webpack-dev-server": "^3.1.14"
},
"dependencies": {
"bootstrap": "^4.1.3"
}
}

Answer 1

It turns out the problem was that I was trying to use extract-text-webpack-plugin which does not work with webpack 4.
Instead, I switched to mini-css-extract-plugin along with optimize-css-assets-webpack-plugin.
My new webpack.config.js file:
const path = require("path");
const config = require('./config.js');
const BrowserSyncPlugin = require('browser-sync-webpack-plugin');
const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
var OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin');
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
module.exports = {
mode: 'production',
entry: ["./src/app.js", "./src/scss/style.scss"],
output: {
path: path.resolve(__dirname, "wp-content/themes/ezdigital"),
filename: "js/[name].js"
},
module: {
rules: [
{
test: /\.scss$/,
use: [
{
loader: "file-loader",
options: {
name: "[name].css"
}
},
{
loader: "extract-loader"
},
{
loader: "css-loader?-url"
},
{
loader: "postcss-loader"
},
{
loader: "sass-loader"
}
]
},
{
test: /\.js$/,
exclude: /(node_modules)/,
use: {
loader: "babel-loader",
options: {
presets: ["env"]
}
}
},
{
test: /\.(png|svg|jpg|gif)$/,
use: ["file-loader"]
}
]
},
//remove comments from JS files
optimization: {
minimizer: [
new UglifyJsPlugin({
uglifyOptions: {
output: {
comments: false,
},
},
}),
new OptimizeCSSAssetsPlugin({
cssProcessorPluginOptions: {
preset: ['default', { discardComments: { removeAll: true } }],
}
})
],
},
plugins: [
new MiniCssExtractPlugin({
filename: "[name].css"
}),
new BrowserSyncPlugin( {
proxy: config.url,
files: [
'**/*.php'
],
reloadDelay: 0
}
)
]
};