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How do I configure Rollup for a React Component Library?

I'm trying to configure Rollup for a React component library (using v3), and am having a real fight. I don't know exactly what I'm doing, but chasing each error just leads to another error. I'm confident that this should be pretty straight forward and is a common use case so I'm hoping someone might be able to help?
Originally I started just with:
const peerDepsExternal = require("rollup-plugin-peer-deps-external");
const resolve = require("#rollup/plugin-node-resolve");
const commonjs = require("#rollup/plugin-commonjs");
const postcss = require("rollup-plugin-postcss");
module.exports = {
input: "src/index.js",
output: {
dir: "build",
format: "esm",
preserveModules: true,
preserveModulesRoot: "src",
sourcemap: true,
},
// external: [/#babel\/runtime/],
plugins: [
resolve(),
commonjs(),
postcss(),
peerDepsExternal(),
],
};
But I hit an error where it was unable to find any JSX files:
Could not resolve "./withSVG" from "src/hoc/index.js"
So I added in the babel JSX plugin:
const jsx = require("rollup-plugin-jsx");
...
plugins: [
resolve(),
jsx({ factory: "React.createElement" }),
commonjs(),
postcss(),
peerDepsExternal(),
]
This then led to another error, where it was unable to parse the chainable operator .?:
[!] (plugin commonjs--resolver) Error: Parse Error: Line 20: Unexpected token .
src/utils/linkStores.js
Error: Parse Error: Line 20: Unexpected token .
So I assumed I needed to insert babel into here somewhere:
const { babel } = require("#rollup/plugin-babel");
...
plugins: [
resolve(),
jsx({ factory: "React.createElement" }),
commonjs(),
babel({
exclude: "node_modules/**",
extensions: [".js", ".jsx"],
}),
postcss(),
peerDepsExternal(),
]
This gave the following message:
babelHelpers: 'bundled' option was used by default. It is recommended to configure this option explicitly, read more here: https://github.com/rollup/plugins/tree/master/packages/babel#babelhelpers
Following the link gives the follow blurb:
'runtime' - you should use this especially when building libraries with Rollup. It has to be used in combination with #babel/plugin-transform-runtime and you should also specify #babel/runtime as dependency of your package. Don't forget to tell Rollup to treat the helpers imported from within the #babel/runtime module as external dependencies when bundling for cjs & es formats. This can be accomplished via regex (external: [/#babel/runtime/]) or a function (external: id => id.includes('#babel/runtime')). It's important to not only specify external: ['#babel/runtime'] since the helpers are imported from nested paths (e.g #babel/runtime/helpers/get) and Rollup will only exclude modules that match strings exactly.
So as I'm trying to create a component library I added:
const babelPluginTransformRuntime = require("#babel/plugin-transform-runtime");
...
plugins: [
babelPluginTransformRuntime,
resolve(),
jsx({ factory: "React.createElement" }),
commonjs(),
babel({
exclude: "node_modules/**",
babelHelpers: "runtime",
extensions: [".js", ".jsx"],
}),
postcss(),
peerDepsExternal(),
]
With a babel.config.js of:
module.exports = {
presets: ["#babel/preset-env", "#babel/preset-react"],
plugins: [
[
"#babel/plugin-transform-react-jsx",
{
runtime: "automatic",
},
],
],
};
But now I get the following error and I can't seem to find any way to resolve this one:
[!] (plugin commonjs--resolver) RollupError: You have declared using "runtime" babelHelpers, but transforming /home/ian/src/chart-it/packages/react/src/index.js resulted in "inline". Please check your configuration.
Can anyone suggest a working rollup config for a react component library (not TypeScript)?
Here's a link to the repository if anyone wants to test an answer: https://github.com/IPWright83/chart-it/tree/fixingPackage

How to use a function in one file that was included globally with webpack

I have a static Javascript project (no react, vue, etc.) where I am trying to transpile, bundle, and minify my js with webpack. I would like to have bundle.js on my layout page which will include a bunch of global js that runs on all pages and then a page_x.js file that will be on individual pages as needed. The bundle.js file might consist of several other files and should be transpiled to es5 and minified.
With my current setup, the files are running twice. I'm not sure how to fix this. I want the file included globally but also want to be able to call the function as needed. If I delete the import statement from page.js I get the console error, "doSomething" is undefined. If I only include page.js on page.html and not on _layout.html common.js is only logged out on page.html. I want "common" to be logged once on every page and I want doSomething() to be available only on page.js.
Here is an example of it running twice:
common.js
console.log("common");
export function doSomething() {
console.log("do something");
}
page.js
import {doSomething} from "/common.js";
$(button).click(doSomething);
The expected output on page load (before clicking anything) would be:
"common"
Instead I'm seeing
"common"
"common"
My webpack.config.js file is as follows:
const path = require("path");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const RemoveEmptyScriptsPlugin = require("webpack-remove-empty-scripts");
const { CleanWebpackPlugin } = require("clean-webpack-plugin");
const WebpackWatchedGlobEntries = require("webpack-watched-glob-entries-plugin");
const CssnanoPlugin = require("cssnano");
const TerserPlugin = require("terser-webpack-plugin");
const dirName = "wwwroot/dist";
module.exports = (env, argv) => {
return {
mode: argv.mode === "production" ? "production" : "development",
entry: WebpackWatchedGlobEntries.getEntries(
[
path.resolve(__dirname, "src/scripts/**/*.js"),
path.resolve(__dirname, "src/scss/maincss.scss")
]),
output: {
filename: "[name].js",
path: path.resolve(__dirname, dirName)
},
devtool: "source-map",
module: {
rules: [
{
test: /\.s[c|a]ss$/,
use:
[
MiniCssExtractPlugin.loader,
"css-loader?sourceMap",
{
loader: "postcss-loader?sourceMap",
options: {
postcssOptions: {
plugins: [
CssnanoPlugin
],
config: true
},
sourceMap: true
}
},
{ loader: "sass-loader", options: { sourceMap: true } },
]
},
{
test: /\.(svg|gif|png|eot|woff|ttf)$/,
use: [
"url-loader",
],
},
{
test: /\.m?js$/,
exclude: /(node_modules|bower_components)/,
use: {
loader: "babel-loader",
options: {
presets: ["#babel/preset-env"]
}
}
}
]
},
plugins: [
new WebpackWatchedGlobEntries(),
new CleanWebpackPlugin(),
new RemoveEmptyScriptsPlugin(),
new MiniCssExtractPlugin({
filename: "[name].css"
})
],
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
extractComments: false,
})
]
}
};
};
Any help would be greatly appreciated.

Webpack is about building a dependency graph of your application files and finally producing one single bundle.
With your configuration, you are actually trying to use Webpack as a Multi-entry object configuration as explained in Webpack documents. The culprit here is WebpackWatchedGlobEntries plugin. For each file matched by a glob pattern, it would create a bundle which is not what you want ever. For exmaple, if you have following structure:
- src/scripts
- common.js
- some
- page1.js
- other
- page2.js
This plugin will produce multi-page application. So, you configuration:
entry: WebpackWatchedGlobEntries.getEntries(
[
path.resolve(__dirname, "src/scripts/**/*.js"),
path.resolve(__dirname, "src/scss/maincss.scss")
]),
will internally return an object as:
entry: {
"common": "src/scripts/common.js",
"some/page1": "src/scripts/some/page1.js",
"other/page2": "src/scripts/other/page2.js"
}
It means if you import common.js into page1.js and page2.js, then you are in producing three bundles and all those bundles will possess the common module which would be executed three times.
The solution really depends on how to you want to configure your bundle:
If you need to bundle as a multi-page application, then you must use splitChunk optimization that allows you to create page specific bundle while keeping shared code separate (common.js for example). Keep in mind that you do not really need to manually create a separate bundle for common.js. with split chunks, Webpack should do that automatically for you.
If you need a single bundle, you can literally go ahead and create a single bundle for entire application (most typical workflow with Webpack) and use the same bundle on each page. You can have a common function like run that can figure the code to call using URL or some unique page specific identifier. In modern SPA, that is done using routing module.
What I will suggest is to keep things simple. Do not use WebpackWatchedGlobEntries plugin. That will complicate things if you are not familiar with Webpack. Keep entry simple like this:
entry: {
// Note that you don't need common module here. It would be picked up as part of your page1 and page2 dependency graph
"page1": "src/scripts/some/page1.js",
"page2": "src/scripts/other/page2.js"
}
Then, enable the splitchunk optimization as:
optimization: {
splitChunks: {
chunks: 'all'
}
}
Again, there are multiple options to choose from. You can read more details here about preventing code duplication.

Override some Webpack 5 NodeJS modules with polyfill

I have NodeJS code that I now need to move to an embedded system. It takes far too long to simply start NodeJS ("Hello World" ~11sec on a BeagleBone Black) so we needed an alternative. The IoT.js looks promising but it does not support some of the internal NodeJS modules (e.g. url, zlib, tty)--which my code needs. I am using Webpack 5.35.0 to create a single file for my code but this is where my problems lie. I want to use Webpack with a node target since IoT.js offers most of what node offers natively. However is there a way to force Webpack to use polyfills for some of the modules? For example, browserify-zlib instead of expecting nodes zlib.
My basic Webpack configuration is simple:
{ target: 'node10.17',
entry: './index.js',
output:
{ filename: 'index.js',
path: '/work/proj/dist',
libraryTarget: 'umd' },
stats: 'errors-only',
resolve:
{ modules: [ '/work/proj/node_modules' ],
extensions: [ '.js', '.json' ],
}
}
I have done some reading where people claim adding a simple resolve.fallback.zlib = false and resolve.alias should do the trick--which is not working for me.
I tried to simply add resolve.fallback.zlib = false in the hopes to just have zlib omitted from the Webpacked output and this did not work. No matter what I do the standard Webpack boilerplate "node" zlib include code exists.
Standard Webpack boilerplate when using node target.
/***/ "zlib":
/*!***********************!*\
!*** external "zlib" ***!
\***********************/
/***/ ((module) => {
"use strict";
module.exports = require("zlib");;
/***/ })
Other things I tried were--ALL of which did not work:
I was hoping this would alias zlib and actually put in the browserify-zlib code.
resolve:
{ modules: [ '/work/proj/node_modules' ],
extensions: [ '.js', '.json' ],
alias: { zlib: '/work/proj/node_modules/browserify-zlib/lib/index.js' },
fallback: {} } }
Same as the previous example but thought by disabling the fallback the alias/polyfill would go into the output. This is what others online had success with.
resolve:
{ modules: [ '/work/proj/node_modules' ],
extensions: [ '.js', '.json' ],
alias: { zlib: '/work/proj/node_modules/browserify-zlib/lib/index.js' },
fallback: { zlib: false } } }
Here I just hoped to not include zlib to see if Webpack would omit it with a node target.
resolve:
{ modules: [ '/work/proj/node_modules' ],
extensions: [ '.js', '.json' ],
fallback: { zlib: false } } }
Lastly I tried to use the plugin node-polyfill-webpack-plugin but with the node target it does not seem to do anything. If I chose a web target the plugin seems to work as I'd expect (taken from here). Again, I'd prefer a node target so it uses native modules and the setup seems cleaner; but maybe this is the only approach. If this is the approach then how to support fs and other non-browser modules that IoT.js supports natively?
...
plugins = [ new NodePolyfillPlugin({ excludeAliases: [] }) ];
It seems that when the node target is selected there is no way to override any of the default/boilerplate code added to the output file. Does anyone have experience with IoT.js and Webpack, or overriding the default Webpack 5 code for node and use a polyfill instead? Not sure if a Webpack plugin is an approach. I am a little new to Webpack. Could this be a problem with Webpack? Any help would be appreciated.

Tree-shaking with rollup

I have a project in which I bundle a components library using Rollup (generating a bundle.esm.js file). These components are then used in another project, that generates web pages which use these components - each page is using different components.
The problem is, that the entire components library is always bundled with the different page bundles, regardless of which components I'm using, unnecessarily increasing the bundle size.
This is my Rollup setup:
import resolve from 'rollup-plugin-node-resolve';
import commonjs from 'rollup-plugin-commonjs';
import babel from 'rollup-plugin-babel';
import peerDepsExternal from 'rollup-plugin-peer-deps-external';
import pkg from './package.json';
const extensions = [
'.js', '.jsx', '.ts', '.tsx',
];
export default [
{
input: './src/base/index.ts',
plugins: [
peerDepsExternal(),
resolve({ extensions }),
babel({
exclude: 'node_modules/**',
extensions,
}),
commonjs(),
],
output: [
{ file: pkg.main, format: 'cjs', sourcemap: true },
{ file: pkg.module, format: 'es', sourcemap: true },
],
watch: {
clearScreen: false,
},
},
];
I have "modules" set to false in webpack, as well.

There are things you will need to do to achieve treeshakable code from both sides - the built package and the project using it.
From your code snippet, I see that you have not add flag preserveModules: true in the rollup config file to prevent the build output from bundling. Webpack can not treeshake a bundled file FYI.
export default {
...
preserveModules: true,
...
}
On the side of the project that using it, you have to specify sideEffects in the package.json - read the doc to know how to config them. Beside that, the optimization in webpack has to has sideEffects: true, also read the doc here.
Hope this helps!

As you don't know which components of your Component Library (CL) will be needed by the adopters repositories you need to export everything but in a way
the adopters can execute a tree-shaking on your CL when they do their own build (and just include what they really need).
In a few words, you have to make your CL, tree-shakable. In order to achieve this, on your CL repo you have to:
Use bundlers that support tree-shaking (rollup, webpack, etc..)
Create the build for modules of type es/esm, NOT commonJS/cjs, etc..
Ensure no transpilers/compilers (babel,tsconfig, etc..) usually used as plugins, transform your ES module syntax to another module syntax.
By the default, the behavior of the popular Babel preset #babel/preset-env may break this rule, see the documentation for more details.
// babelrc.json example that worked for me
[
"#babel/preset-env",
{
"targets": ">0.2%, not dead, not op_mini all"
}
],
In the codebase, you always have to use import/export (no require) syntax, and import specifically the things you need only.
import arrayUtils from "array-utils"; //WRONG
import { unique, implode, explode } from "array-utils"; //OK
Configure your sideEffects on the package.json.
"sideEffects": ["**/*.css"], //example 1
"sideEffects": false, //example 2
DO NOT create a single-bundle file but keep the files separated after your build process (official docs don't say this but was the only solution that worked for me)
// rollup.config.js example
const config = [
{
input: 'src/index.ts',
output: [
{
format: 'esm', // set ES modules
dir: 'lib', // indicate not create a single-file
preserveModules: true, // indicate not create a single-file
preserveModulesRoot: 'src', // optional but useful to create a more plain folder structure
sourcemap: true, //optional
},
],
... }]
Additionally, you may need to change your module entry point in order the adopters can directly access to the proper index.js file where you are exporting everthing:
// package.json example
{
...
"module": "lib/index.js", //set the entrypoint file
}
Note: Remember that tree-shaking is executed by an adopter repository that has a build process that supports tree-shaking (eg: a CRA repo) and usually tree-shaking is just executed on prod mode (npm run build), no on dev mode. So be sure to properly test if this is working or not.

Moment failed to work with webpack (typescript + babel)

Just as the demo, when i add moment to the project, bundle built by webpack failed, once i remove the moment it is ok.
Note: the module in tsconfig.json is set to es6, which is exactly what i need, when switch it to commonjs, it is ok too.
I am told you guys are acitve here, thanks very much to you~~~

After got it running and disable minify mode, I saw that problem is how you using moment. You can use this config to see your unminify code problem:
entry: './src/index.tsx',
mode: 'production',
output: {
path: path.join(__dirname, 'lib'),
filename: 'index.js',
},
module: {
rules: [
{
test: /\.(tsx|ts)$/,
exclude: /node_modules/,
use: ['babel-loader', 'ts-loader'],
},
],
},
optimization: {
// We no not want to minimize our code.
minimize: false
},
After change, I got error moment is not a function. So it's a problem when webpack bundle and how moment export their function
https://github.com/palantir/blueprint/issues/959
You can fix it by
const moment = require('moment')
to use the function as document or
moment.toString()
to just got the current time.
Or change options in tsconfig like in https://momentjs.com/docs/#/use-it/typescript/