We Keep Coding

Webpack HMR for Node.js

I use webpack to bundle my nodejs code. As well known, we could use webpack-dev-server to build an environment for dev, so how about nodejs? I know nodemon can work, but it restart the whole project, I want a HMR way.

You can follow this:
run npm i --save-dev webpack-node-externals run-script-webpack-plugin webpack
create a webpack-hmr.config.js file in the root directory of your application and put this:
const nodeExternals = require('webpack-node-externals');
const { RunScriptWebpackPlugin } = require('run-script-webpack-plugin');
module.exports = function (options, webpack) {
return {
...options,
entry: ['webpack/hot/poll?100', options.entry],
externals: [
nodeExternals({
allowlist: ['webpack/hot/poll?100'],
}),
],
plugins: [
...options.plugins,
new webpack.HotModuleReplacementPlugin(),
new webpack.WatchIgnorePlugin({
paths: [/\.js$/, /\.d\.ts$/],
}),
new RunScriptWebpackPlugin({ name: options.output.filename }),
],
};
};
inside your main.js:
async function bootstrap() {
<Your Express middleware and etc>
if (module.hot) {
module.hot.accept();
module.hot.dispose(() => server.close());
}
}
inspired by Nest.js HMR

Using webpack for copying file if it is on localhost, else minifying

I am new to Webpack.
My team is using Golang for the server, and starting to use ReactJS + MobX on the front end. We use Webpack to bundle/transpile all the code into one bundle file per page. (It is multipage application.)
My PM has me looking into moving all this front-end code from static to a new folder called src, and to do the following:
setup the environment such that:
if running localhost, simply copy the files to that folder (we're debugging it)
else, minify the files to that folder (we don't want the end user to be able to reverse-engineer our stuff/see its source code)
Since Golang is running the server and not Webpack (our use case is merely the transpilation at development time), is there way that I can get Webpack to work like this?
NOTE: our entry files are not necessarily on the same level, but have path like static/js/[relative path of one or more levels]/entry.js

Use webpack merge you can do that
Basically you will need 3 file
Main webpack.config.js file
webpack.dev.js for dev enviroment
webpack.prod.js for production enviroment
Example: webpack.dev.js
const merge = require('webpack-merge');
const baseConfig = require('./webpack.config.js');
const webpack = require("webpack");
module.exports = merge(baseConfig, {
plugins: [
new webpack.DefinePlugin({
'process.env': {
'NODE_ENV': JSON.stringify('development'),
'BASE_URL': JSON.stringify('http://localhost:5000/')
}
})
],
watch: true
});
webpack.prod.js. You can see that I'm using some optimization packge in prod mode only like OptimizeCSSAssetsPlugin, CompressionPlugin, UglifyJsPlugin to uglify and gzip the file content to improve performance. You can adjust accordingly with your need.
const OptimizeCSSAssetsPlugin = require("optimize-css-assets-webpack-plugin");
const UglifyJsPlugin = require("uglifyjs-webpack-plugin");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const CompressionPlugin = require("compression-webpack-plugin");
const merge = require('webpack-merge');
const baseConfig = require('./webpack.config.js');
const webpack = require("webpack");
module.exports = merge(baseConfig, {
optimization: {
minimizer: [
new UglifyJsPlugin({
cache: true,
parallel: true,
sourceMap: false,
extractComments: 'all',
uglifyOptions: {
compress: true,
output: null
}
}),
new OptimizeCSSAssetsPlugin({
cssProcessorOptions: {
safe: true,
discardComments: {
removeAll: true,
},
},
})
]
},
plugins: [
new webpack.DefinePlugin({
'process.env': {
'NODE_ENV': JSON.stringify('production'),
'BASE_URL': JSON.stringify('a/')
}
}),
new CompressionPlugin({
test: /\.(js|css)/
}),
new UglifyJsPlugin(),
]
});
To run it simply use these 2 command in your package.json
"prod": "webpack -p --mode=production --config webpack.prod.js",
"start": "webpack --mode=development --config webpack.dev.js",

Webpack - Excluding node_modules with also keep a separated browser and server management

(webpack.config.js file content below)
I'm trying to make a webpack exclusion on node modules.
I found that using webpack-node-externals works for it but using that on my common config causes this other error:
Require is not defined on reflect-metadata - __webpack_require__ issue
So... I was wondering how can i exclude webpack bundling also on the browser side without getting any issue.
My webpack version: 3.11.0
webpack-config.js
const path = require('path');
const webpack = require('webpack');
const merge = require('webpack-merge');
const AotPlugin = require('#ngtools/webpack').AotPlugin;
const CheckerPlugin = require('awesome-typescript-loader').CheckerPlugin;
var nodeExternals = require('webpack-node-externals');
module.exports = (env) => {
// Configuration in common to both client-side and server-side bundles
const isDevBuild = !(env && env.prod);
const sharedConfig = {
//externals: [nodeExternals()], // in order to ignore all modules in node_modules folder
stats: { modules: false },
context: __dirname,
resolve: { extensions: [ '.js', '.ts' ] },
output: {
filename: '[name].js',
publicPath: 'dist/' // Webpack dev middleware, if enabled, handles requests for this URL prefix
},
module: {
rules: [
{ test: /\.ts$/, use: isDevBuild ? ['awesome-typescript-loader?silent=true', 'angular2-template-loader', 'angular2-router-loader'] : '#ngtools/webpack' },
{ test: /\.html$/, use: 'html-loader?minimize=false' },
{ test: /\.css$/, use: [ 'to-string-loader', 'style-loader', isDevBuild ? 'css-loader' : 'css-loader?minimize' ] },
{ test: /\.(png|jpg|jpeg|gif|svg)$/, use: 'url-loader?limit=25000' }
]
},
plugins: [new CheckerPlugin()]
};
// Configuration for client-side bundle suitable for running in browsers
const clientBundleOutputDir = './wwwroot/dist';
const clientBundleConfig = merge(sharedConfig, {
entry: { 'main-client': './ClientApp/boot.browser.ts' },
output: { path: path.join(__dirname, clientBundleOutputDir) },
plugins: [
new webpack.DllReferencePlugin({
context: __dirname,
manifest: require('./wwwroot/dist/vendor-manifest.json')
})
].concat(isDevBuild ? [
// Plugins that apply in development builds only
new webpack.SourceMapDevToolPlugin({
filename: '[file].map', // Remove this line if you prefer inline source maps
moduleFilenameTemplate: path.relative(clientBundleOutputDir, '[resourcePath]') // Point sourcemap entries to the original file locations on disk
})
] : [
// Plugins that apply in production builds only
new webpack.optimize.UglifyJsPlugin(),
new AotPlugin({
tsConfigPath: './tsconfig.json',
entryModule: path.join(__dirname, 'ClientApp/app/app.browser.module#AppModule'),
exclude: ['./**/*.server.ts']
})
])
});
// Configuration for server-side (prerendering) bundle suitable for running in Node
const serverBundleConfig = merge(sharedConfig, {
resolve: { mainFields: ['main'] },
entry: { 'main-server': './ClientApp/boot.server.ts' },
plugins: [
new webpack.DllReferencePlugin({
context: __dirname,
manifest: require('./ClientApp/dist/vendor-manifest.json'),
sourceType: 'commonjs2',
name: './vendor'
})
].concat(isDevBuild ? [] : [
// Plugins that apply in production builds only
new AotPlugin({
tsConfigPath: './tsconfig.json',
entryModule: path.join(__dirname, 'ClientApp/app/app.server.module#AppModule'),
exclude: ['./**/*.browser.ts']
})
]),
output: {
libraryTarget: 'commonjs',
path: path.join(__dirname, './ClientApp/dist')
},
target: 'node',
externals: [nodeExternals()], // in order to ignore all modules in node_modules folder,
devtool: 'inline-source-map'
});
return [clientBundleConfig, serverBundleConfig];
};

GOT IT!
Before posting my solution, I'd like to thanks Aluan Haddad for his useful comment in my question above.
As suggested by Aluan, in fact, the problem was related to the need to use also a module loader, more than a module bundler.
So, the steps that I followed are these:
Installing requireJS ==> http://requirejs.org/docs/node.html
Removing externals: [nodeExternals()], // in order to ignore all modules in node_modules folder from my common webpack configuration and adding it under my server configuration (done before my question, but it's a really important step) [see webpack.config.js content in the question]
Adding target: 'node', before my externals point above, under my server side section (done before my question, but it's a really important step) [see webpack.config.js content in the question]
This makes sure that browser side keeps target:'web' (default target), and target becomes node just for the server.
launched webpack config vendor command manually from powershell webpack --config webpack.config.vendor.js
launched webpack config command manually from powershell webpack --config webpack.config.js
That worked for me! Hope It will works also for anyone else reading this question and encountering this issue!

How do i prevent a .js file being bundled by webpack

Hi I am currently using webpack to bundle my project files into a single file. However, I do not want webpack to bundle my config.js file where all my config is set. I would like to this remain separate in the output folder but not sure out to achieve this.
my current setup is
//index.js file
#!/usr/bin/env node
'use strict';
let config = require('config.js);
let read = require('read.js);
console.log('i am running through command line');
//read.js file
'use strict'
console.log('read a text file');
//config.js
'use strict';
module.exports = {
name: 'test'
}
//webpack.config.js
let webpack = require('webpack');
let path = require('path');
let fs = require('fs');
let nodeModules = {};
fs.readdirSync('node_modules')
.filter(function (x) {
return [ '.bin' ].indexOf(x) === -1;
})
.forEach(function (mod) {
nodeModules[mod] = 'commonjs ' + mod;
});
module.exports = {
entry: [ 'babel-polyfill', './index.js' ],
target: 'node',
node: {
__dirname: true
},
output: {
path: path.join(__dirname, 'webpack_bundle'),
filename: '[name].js',
libraryTarget: 'commonjs'
},
module: {
loaders: [
{
test: /\.js$/,
loader: 'shebang-loader'
},
{
test: /\.js$/,
loader: 'babel-loader',
query: {
presets: [ 'es2015' ]
}
} ]
},
resolve: {
extensions: [ '.js' ]
},
plugins: [
new webpack.BannerPlugin({banner: '#!/usr/bin/env node', raw: true
})
]
,
externals: nodeModules
};
Note: I have significantly simplified the code example for brevity
Currently when i run the webpack command i get a folder webpack_bundle which contains an index.js file - the index.js file includes the dependencies config.js and read.js. However, what i would like is for the read.js dependency to be bundled into the index.js file but the config.js dependency to stay external in a separate file which gets required by the bundled webpack output. So the folder webpack_bundle should contain two files after running the webpack command - index.js and config.js. I have already tried to modify the externals by adding the following key value to the externals object config: './config.js' but this did not work. I also created an extra entrypoint by specifying config.js as the entrypoint but this also did not work. I can't figure this out and the webpack docs are not that clear on how to achieve this. Please help!

If you want your config in a separate bundle, you can create a split point, by importing dynamically your config.js file with require.ensure:
require.ensure([], function() {
let config = require('./config.js');
});
Your config will then be in a separate bundle.
Documentation about Code splitting (warning: Webpack 1.x is deprecated).
Documentation about Code Splitting (Webpack 2).
Edit:
If you don't want your config file to be bundled by Webpack, I think you can use IgnorePlugin:
module.exports = {
//...
plugins: [new webpack.IgnorePlugin(/^\.\/config\.js$/)]
}
And use copy-webpack-plugin to copy your config.js file.

Delete unused webpack chunked files

I'm looking for information on how to delete old webpack chunked files. Here is my current webpack configuration:
var path = require('path');
var webpack = require('webpack');
module.exports = {
debug: false,
outputPathinfo: true,
displayErrorDetails: true,
context: __dirname,
entry: {
common: ['./src/common.coffee'],
a: './src/a.cjsx',
b: './src/b.cjsx'
},
output: {
filename: '[name]-[chunkhash].js',
chunkFileName: '[name].[chunkhash].js',
path: path.join(__dirname, 'js')
},
plugins: [
new webpack.optimize.CommonsChunkPlugin('common', 'common-[chunkhash].js'),
new webpack.optimize.UglifyJsPlugin({
compress: { warnings: false }
})
],
module: {
preLoaders: [
{
test: /\.coffee$/,
exclude: /node_modules/,
loader: 'coffeelint-loader'
}
],
loaders: [
{ test: /\.coffee/, loader: 'coffee' },
{ test: /\.cjsx$/, loaders: ['coffee', 'cjsx'] },
{ test: /\.js$/, loader: 'jsx-loader?harmony' }
]
}
}
If I am running $(npm bin)/webpack --config webpack.js --watch and make changes to a.cjsx, it compiles a newer version of that file with a new chunkedhash. However, the old one remains and I'd like it to be deleted right away.
How can I delete the old version of the chunked file?
Is there a way for me to hook into an after callback once watch finishes compiling?

There is a clean-webpack-plugin for those purposes, or you can write a simple bash script for npm:
"scripts": {
"build": "rm -r dist/* && webpack -p",
"clean": "rm -r dist/*"
}

Here is the webpack-clean-obsolete-chunks plugin, which do what you want. It searches for all updated chunks and deletes obsolete files after each webpack compilation.

The answer
I've decided to write an answer because others - although trying to answer the question directly - overlooked the most important part in my opinion.
And the most important part is: you shouldn't be doing it this way. Using [hash] placeholders in your development setup cause many headaches with other tooling (phpstorm's path autocomplete in symfony plugin for example). Also it's poor for webpack's incremental compilation performance and thus is not recommended by official webpack docs (reference).
So for future readers: just keep it simple for development config - define your filename as [name].js and move on.
Edit
There seems to be a confusion about what to do with the old chunk-files on the production server. Well, you don't do anything. Once a version is deployed it shouldn't be ever changed. You just keep creating new versions when deploying and keep previous as a backup. Why?
Because you want you're rollback to be reliable and for it to be possible your rollback needs to be extremely simple and atomic. If your rollback procedure is doing anything more than switching a symlink, rerouting to previous container (or similar simple operation) you're probably™ going to end up in trouble.
Rollback isn't a process of "re-deploying" the application again, but now to the previous version. It's a process of "un-doing" the deployment. So doing a git checkout to the previous version followed by a npm build --but-please-be-hurry --and-im-begging-you-dont-fail while your production app is hanging there, completely exploded doesn't cut here.
Rebuilding a previous version of the application - just like the deployment - may fail for many reasons. That's why a rollback should be switching/rerouting back to the exact same version-build that is proven to be working. Not ==-the-same, 100% ===-the-same. That's why you need to keep your previous version around, because that's the ===-same. A "regenerated" one is - in best case scenario - only ==-the-same, and so it is not proven to be working, only assumed.
And no, no amount of CI, staging environments or whatever will give you a guaranteed successful deployment. Part of doing it the right way is to be prepared for when things go wrong. And things will go wrong. Hopefully only from time to time, but still.
Of course once you have 3, 5 or <put-your-number-here> versions backed up you may start to remove the oldest ones as you probably won't ever need more than 3.

Since Webpack 5.20.0 you can use output.clean option

Take a look at this pull request:
https://github.com/johnagan/clean-webpack-plugin/pull/32/files
Open raw file view and copy it to index.js of clean webpack plugin.
Remember about config flag -> watch: true

I have solved that problem by adding below in webpack.config.js
const { CleanWebpackPlugin } = require('clean-webpack-plugin');
{
... your configs ...
plugins: [new CleanWebpackPlugin()]
}

You can solve the problem № 1 by using remove-files-webpack-plugin.
Use this plugin like this:
plugins: [
new RemovePlugin({
watch: {
test: [
{
folder: './js',
method: (absPath) => new RegExp(/(.*)-([^-\\\/]+)\.js/).test(absPath)
}
]
}
})
]
In "watch" mode (not normal compilation!) it grabs all files from ./js folder and tests them with this regular expression /(.*)-([^-\\\/]+)\.js/. Analyze this regular expression on regex101 (unit tests are included) if you have problems with understanding.
Note: i'm the creator of this plugin.

Looks like webpack#5.20.0+ has built-in support for this https://webpack.js.org/configuration/output/#outputclean. I use [chunkhash] in my chunk filenames and they get cleared out if I stop comment out dynamic imports and added back in if I uncomment them.

my case: webpack 5 + multipage application + themes.css via entry points
solution: https://github.com/webdiscus/webpack-remove-empty-scripts
this plugins don't work with webpack 5 entry points or with MiniCssExtractPlugin:
webpack-fix-style-only-entries,
webpack-extraneous-file-cleanup-plugin,
webpack-remove-empty-js-chunks-plugin,
webpack-delete-no-js-entries-plugin.
my webpack.config.js:
const fs = require('fs');
const path = require('path');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const RemoveEmptyScriptsPlugin = require('webpack-remove-empty-scripts');
const isProd = process.env.NODE_ENV === 'production';
const isDev = !isProd;
const PAGES = ['app', 'help'];
const getThemes = (themePath, alias) => {
let themes = {};
const longPath = './' + alias + '/' + themePath;
fs.readdirSync(longPath).forEach(function(fileName) {
const fileNameWithPath = path.join(themePath, fileName);
const fileNameWithLongPath = path.join(longPath, fileName);
const stat = fs.lstatSync(fileNameWithLongPath);
if (stat.isDirectory()) return;
if (!/\.scss$/.test(fileName)) return;
const nameWithoutExt = path.basename(fileName, '.scss');
themes[nameWithoutExt] = ['./' + fileNameWithPath];
});
console.log(themes);
return themes;
};
const themes = getThemes('scss/themes', 'src');
const getFilename = (filename, ext) => {
let name = filename == 'index' ? 'bundle' : filename;
const isTheme = (ext == 'css' && name.startsWith('theme')) ? true : false;
const needHash = (isDev || isTheme) ? false : true;
return needHash ? name +`.[fullhash].` + ext : name+'.'+ext;
};
const getCSSDirname = filename => {
const isTheme = filename.startsWith('theme');
return !isTheme? '/css/' : '/css/theme/';
};
const getHTMLWebpackPlugins = arr => {
// this function config multipages names and add to html-pages
// inside <head> tag our themes via tag <link rel="stylesheet" href="....css" ...>
// and return array of HTMLWebpackPlugins
};
module.exports = {
// ... //
entry: {
// mutipage:
app: ['./index.js', './scss/app.scss'],
help: ['./help.js', './scss/help.scss'],
// multitheme:
...themes,
},
optimization: {
removeEmptyChunks: true, // not work!!!
},
// ... //
plugins: [
// ... //
...getHTMLWebpackPlugins(PAGES),
new RemoveEmptyScriptsPlugin({
ignore: PAGES,
enabled: isDev === false,
}),
new MiniCssExtractPlugin({
filename: pathdata => {
return getCSSDirname(pathdata.chunk.name) + getFilename(pathdata.chunk.name, 'css');
},
chunkFilename: isDev ? '[id].css' : '[id].[contenthash].css',
}),
],
};
my src files:
[src]:
- index.js
- index.html
- help.js
- help.html
- [scss]:
- - app.scss
- - help.scss
- - [themes]:
- - - light.scss
- - - dark.scss
- - - blue.scss
after build:
[dist]:
- app.js
- index.html
- help$hash.js
- help$hash.html
- [css]:
- - app$hash.css
- - help$hash.css
- - [themes]:
- - - light.css
- - - dark.css
- - - blue.css

For Windows users
"scripts": {
"build": "npm run clean && webpack --mode production",
"clean": "del /f /s /q dist 1>nul"
}

I just had to stop my server and run yarn serve again