I have three packages inside standard lerna monorepo.
client
react library
core
Core - is a shared component library with some utils (may or may not publish on npm).
React library is component library which will be shared on npm.
client is a bundled js library which will be consumed in browser with static html files.
core is a dependency in react-lib as well as client
Question 1 - How to setup core, should I transpile with tsc and bundle with tools such as rollup or vite (i personally prefer vite/rollup over webpack). or just leave it as is and import it in client and react-lib with absolute paths like 'core/src/*"?
Question 2 - can i build core in 'es' format and build client just like normal react app with either cra or vite. I tried this but i think i am missing something as final bundle doesn't seem to work in browser.
Any help would be really appreciated.
You have a few questions and I might not be able to answer them all but hopefully enough to guide you for the solution you're looking for.
Core - is a shared component library with some utils (may or may not publish on npm).
If you want to use Lerna then I guess you'll have to eventually publish the package on npm or a private repository. As an alternative, you could also use pnpm workspaces and their workspace: protocol which will allow you to link the packages in your workspace (monorepo) without ever downloading them from npm, for example if you use workspace:* then it will always use and link to the latest code from your local workspace. You could also use workspace: protocol with Lerna (or Lerna-Lite) since they both support it.
For your next Questions, I'll answer the last part of your Question 1 first because that affects the other portion of the question.
Question 1: ...or just leave it as is and import it in client and react-lib with absolute paths like 'core/src/*'?
Use absolute paths outside of the package is not a good thing to do since it will only work on your local project and you cannot publish that to npm since it will be broken for the other users. It's better to stick with the workspace and let the package use the main or exports entries defined in your package.json. In other words, it's preferable to always build/transpile and let your other package use the transpiled code and if you need to debug then make sure to also include sourcemap
Question 1: How to setup core, should I transpile with tsc and bundle with tools such as rollup or vite (i personally prefer vite/rollup over webpack)
It probably doesn't matter which one you use TypeScript, Rollup or WebPack, In one of my project I use TypeScript in watch mode, it will auto-transpile whenever you change your code, the downside is that the more packages you have then the more TypeScript threads are opened in watch mode (1x per package) but in your case if you only have 3 then it's fine, there's also this TypeScript issue that I'm following which will hopefully bring multi-threaded compilation in the future. You could also use Rollup and the concept would be the same, use it in watch mode for each package (I've done it with Vite/Rollup using vite build --watch
as explained in the next paragraph).
You can take a look at a project I've done Vue 3 and pnpm workspace using pnpm workspace with the workspace: protocol, it uses Rollup for transpiling and also uses Vite library mode which allows to bundle your library for distribution (on npm or others...), this allows you to bundle each package as a lib that is easily reusable by other projects. It's a Vue 3 project, so it's not a React project but it should give you enough ideas on how to do in React and it should help to answer your Question 2. Also that project is not using Lerna/Lerna-Lite but since it uses the workspace: protocol then it would be super easy to add Lerna on top of it in the future (basically just adding the lerna.json config should be enough)
I'm studying React, and would like to know how best way to create a private component to reuse it in other projects.
Thanks!
Probably npm private package is what you are looking for. Then, you can just install your package by npm install and use components from it everywhere you want. However, this is paid feature of npm.
The alternative is an npm proxy registry. For example Verdaccio allows something like that. Similiar solution to the previous one, but you have to configure the registry yourself and use it in all your projects instead of default npm registry.
You can also just publish a public npm package if it's ok for you that it'll be available for everyone. It's probably the easiest solution for starters.
Alternatively, what we used in our project, were Git submodules. You place your shared components into a separate Git repository. Then, you link that as a submodule in you main project and you can use your components just like they were a part of your project. If you use Git, it might be the easiest option for you.
And finally, if you treat you projects as playground, you always can use copy-paste approach :) I don't recommend it in any commercial projects as maintaining the code in many places is pain in the neck.
I want to use my UI components as a reusable seperate repo/project for my react-native iniit App.
So i creatd a seperate project folder like this
and installed these dependencies
and few dependencies externally with my other app.
Then i used
yarn link
to link this project to my working app as a module just like a node module. but i get this error when i try to run my app?
Is there an issue with my method, or is there a sure way i can try to reach my goal because i found multiple ways and various configuration of creating such component libraries.but i didn't use any since the end goal is different.
This is a known issue with the React Native packager. See this discussion: https://github.com/facebook/react-native/issues/637.
This may have to do with using watchman, although there seem to be a few different cases where this can crop up.
TL;DR: React Native packager does not respect symlinks to projects, so npm and yarn link do not work like you would expect them to. Apparently this is being resolved in metro-bundler: https://github.com/facebook/metro-bundler/issues/1.
Unfortunately the workarounds are not that pretty, but there are a few options discussed in the issue 637 discussion. It also looks like you may be using a github repo for your package.
You could tell npm to get your library from github via your project's package.json, so you probably do not need npm link, though you will not be able to link to your local files for your module this way.
I want to split my web project into three: front-end, back-end and super-admin.
What is the best way to re-use the components across code bases? Npm packages? That seems hard to maintain:
Open component dev package
Make changes
Push changes
Tag version
Update all projects
Seems complex and prone to errors. Is there a better way?
Depends on if you need to use different versions of the shared components from different projects. If so, you probably need to make a versioned npm package. However, if you just want to share the packages and use the same version everywhere, you have other options. For one, you don't have to actually build and publish an npm packge, you can just use npm link. This will basically create a symlink to your shared code in node_modules of the other projects.
Alternatively, you can do it without any npm package at all, just have the shared components in a separate project (directory) and import them in javascript through an alias, using a bundling system (webpack alias / browserify aliasify).
What is the fundamental difference between bower and npm? Just want something plain and simple. I've seen some of my colleagues use bower and npm interchangeably in their projects.
All package managers have many downsides. You just have to pick which you can live with.
History
npm started out managing node.js modules (that's why packages go into node_modules by default), but it works for the front-end too when combined with Browserify or webpack.
Bower is created solely for the front-end and is optimized with that in mind.
Size of repo
npm is much, much larger than bower, including general purpose JavaScript (like country-data for country information or sorts for sorting functions that is usable on the front end or the back end).
Bower has a much smaller amount of packages.
Handling of styles etc
Bower includes styles etc.
npm is focused on JavaScript. Styles are either downloaded separately or required by something like npm-sass or sass-npm.
Dependency handling
The biggest difference is that npm does nested dependencies (but is flat by default) while Bower requires a flat dependency tree (puts the burden of dependency resolution on the user).
A nested dependency tree means that your dependencies can have their own dependencies which can have their own, and so on. This allows for two modules to require different versions of the same dependency and still work. Note since npm v3, the dependency tree will be flat by default (saving space) and only nest where needed, e.g., if two dependencies need their own version of Underscore.
Some projects use both: they use Bower for front-end packages and npm for developer tools like Yeoman, Grunt, Gulp, JSHint, CoffeeScript, etc.
Resources
Nested Dependencies - Insight into why node_modules works the way it does
This answer is an addition to the answer of Sindre Sorhus. The major difference between npm and Bower is the way they treat recursive dependencies. Note that they can be used together in a single project.
On the npm FAQ: (archive.org link from 6 Sep 2015)
It is much harder to avoid dependency conflicts without nesting
dependencies. This is fundamental to the way that npm works, and has
proven to be an extremely successful approach.
On Bower homepage:
Bower is optimized for the front-end. Bower uses a flat dependency
tree, requiring only one version for each package, reducing page load
to a minimum.
In short, npm aims for stability. Bower aims for minimal resource load. If you draw out the dependency structure, you will see this:
npm:
project root
[node_modules] // default directory for dependencies
-> dependency A
-> dependency B
[node_modules]
-> dependency A
-> dependency C
[node_modules]
-> dependency B
[node_modules]
-> dependency A
-> dependency D
As you can see it installs some dependencies recursively. Dependency A has three installed instances!
Bower:
project root
[bower_components] // default directory for dependencies
-> dependency A
-> dependency B // needs A
-> dependency C // needs B and D
-> dependency D
Here you see that all unique dependencies are on the same level.
So, why bother using npm?
Maybe dependency B requires a different version of dependency A than dependency C. npm installs both versions of this dependency so it will work anyway, but Bower will give you a conflict because it does not like duplication (because loading the same resource on a webpage is very inefficient and costly, also it can give some serious errors). You will have to manually pick which version you want to install. This can have the effect that one of the dependencies will break, but that is something that you will need to fix anyway.
So, the common usage is Bower for the packages that you want to publish on your webpages (e.g. runtime, where you avoid duplication), and use npm for other stuff, like testing, building, optimizing, checking, etc. (e.g. development time, where duplication is of less concern).
Update for npm 3:
npm 3 still does things differently compared to Bower. It will install the dependencies globally, but only for the first version it encounters. The other versions are installed in the tree (the parent module, then node_modules).
[node_modules]
dep A v1.0
dep B v1.0
dep A v1.0 (uses root version)
dep C v1.0
dep A v2.0 (this version is different from the root version, so it will be an nested installation)
For more information, I suggest reading the docs of npm 3
TL;DR: The biggest difference in everyday use isn't nested dependencies... it's the difference between modules and globals.
I think the previous posters have covered well some of the basic distinctions. (npm's use of nested dependencies is indeed very helpful in managing large, complex applications, though I don't think it's the most important distinction.)
I'm surprised, however, that nobody has explicitly explained one of the most fundamental distinctions between Bower and npm. If you read the answers above, you'll see the word 'modules' used often in the context of npm. But it's mentioned casually, as if it might even just be a syntax difference.
But this distinction of modules vs. globals (or modules vs. 'scripts') is possibly the most important difference between Bower and npm. The npm approach of putting everything in modules requires you to change the way you write Javascript for the browser, almost certainly for the better.
The Bower Approach: Global Resources, Like <script> Tags
At root, Bower is about loading plain-old script files. Whatever those script files contain, Bower will load them. Which basically means that Bower is just like including all your scripts in plain-old <script>'s in the <head> of your HTML.
So, same basic approach you're used to, but you get some nice automation conveniences:
You used to need to include JS dependencies in your project repo (while developing), or get them via CDN. Now, you can skip that extra download weight in the repo, and somebody can do a quick bower install and instantly have what they need, locally.
If a Bower dependency then specifies its own dependencies in its bower.json, those'll be downloaded for you as well.
But beyond that, Bower doesn't change how we write javascript. Nothing about what goes inside the files loaded by Bower needs to change at all. In particular, this means that the resources provided in scripts loaded by Bower will (usually, but not always) still be defined as global variables, available from anywhere in the browser execution context.
The npm Approach: Common JS Modules, Explicit Dependency Injection
All code in Node land (and thus all code loaded via npm) is structured as modules (specifically, as an implementation of the CommonJS module format, or now, as an ES6 module). So, if you use NPM to handle browser-side dependencies (via Browserify or something else that does the same job), you'll structure your code the same way Node does.
Smarter people than I have tackled the question of 'Why modules?', but here's a capsule summary:
Anything inside a module is effectively namespaced, meaning it's not a global variable any more, and you can't accidentally reference it without intending to.
Anything inside a module must be intentionally injected into a particular context (usually another module) in order to make use of it
This means you can have multiple versions of the same external dependency (lodash, let's say) in various parts of your application, and they won't collide/conflict. (This happens surprisingly often, because your own code wants to use one version of a dependency, but one of your external dependencies specifies another that conflicts. Or you've got two external dependencies that each want a different version.)
Because all dependencies are manually injected into a particular module, it's very easy to reason about them. You know for a fact: "The only code I need to consider when working on this is what I have intentionally chosen to inject here".
Because even the content of injected modules is encapsulated behind the variable you assign it to, and all code executes inside a limited scope, surprises and collisions become very improbable. It's much, much less likely that something from one of your dependencies will accidentally redefine a global variable without you realizing it, or that you will do so. (It can happen, but you usually have to go out of your way to do it, with something like window.variable. The one accident that still tends to occur is assigning this.variable, not realizing that this is actually window in the current context.)
When you want to test an individual module, you're able to very easily know: exactly what else (dependencies) is affecting the code that runs inside the module? And, because you're explicitly injecting everything, you can easily mock those dependencies.
To me, the use of modules for front-end code boils down to: working in a much narrower context that's easier to reason about and test, and having greater certainty about what's going on.
It only takes about 30 seconds to learn how to use the CommonJS/Node module syntax. Inside a given JS file, which is going to be a module, you first declare any outside dependencies you want to use, like this:
var React = require('react');
Inside the file/module, you do whatever you normally would, and create some object or function that you'll want to expose to outside users, calling it perhaps myModule.
At the end of a file, you export whatever you want to share with the world, like this:
module.exports = myModule;
Then, to use a CommonJS-based workflow in the browser, you'll use tools like Browserify to grab all those individual module files, encapsulate their contents at runtime, and inject them into each other as needed.
AND, since ES6 modules (which you'll likely transpile to ES5 with Babel or similar) are gaining wide acceptance, and work both in the browser or in Node 4.0, we should mention a good overview of those as well.
More about patterns for working with modules in this deck.
EDIT (Feb 2017): Facebook's Yarn is a very important potential replacement/supplement for npm these days: fast, deterministic, offline package-management that builds on what npm gives you. It's worth a look for any JS project, particularly since it's so easy to swap it in/out.
EDIT (May 2019)
"Bower has finally been deprecated. End of story." (h/t: #DanDascalescu, below, for pithy summary.)
And, while Yarn is still active, a lot of the momentum for it shifted back to npm once it adopted some of Yarn's key features.
2017-Oct update
Bower has finally been deprecated. End of story.
Older answer
From Mattias Petter Johansson, JavaScript developer at Spotify:
In almost all cases, it's more appropriate to use Browserify and npm over Bower. It is simply a better packaging solution for front-end apps than Bower is. At Spotify, we use npm to package entire web modules (html, css, js) and it works very well.
Bower brands itself as the package manager for the web. It would be awesome if this was true - a package manager that made my life better as a front-end developer would be awesome. The problem is that Bower offers no specialized tooling for the purpose. It offers NO tooling that I know of that npm doesn't, and especially none that is specifically useful for front-end developers. There is simply no benefit for a front-end developer to use Bower over npm.
We should stop using bower and consolidate around npm. Thankfully, that is what is happening:
With browserify or webpack, it becomes super-easy to concatenate all your modules into big minified files, which is awesome for performance, especially for mobile devices. Not so with Bower, which will require significantly more labor to get the same effect.
npm also offers you the ability to use multiple versions of modules simultaneously. If you have not done much application development, this might initially strike you as a bad thing, but once you've gone through a few bouts of Dependency hell you will realize that having the ability to have multiple versions of one module is a pretty darn great feature. Note that npm includes a very handy dedupe tool that automatically makes sure that you only use two versions of a module if you actually have to - if two modules both can use the same version of one module, they will. But if they can't, you have a very handy out.
(Note that Webpack and rollup are widely regarded to be better than Browserify as of Aug 2016.)
Bower maintains a single version of modules, it only tries to help you select the correct/best one for you.
Javascript dependency management : npm vs bower vs volo?
NPM is better for node modules because there is a module system and you're working locally.
Bower is good for the browser because currently there is only the global scope, and you want to be very selective about the version you work with.
My team moved away from Bower and migrated to npm because:
Programmatic usage was painful
Bower's interface kept changing
Some features, like the url shorthand, are entirely broken
Using both Bower and npm in the same project is painful
Keeping bower.json version field in sync with git tags is painful
Source control != package management
CommonJS support is not straightforward
For more details, see "Why my team uses npm instead of bower".
Found this useful explanation from http://ng-learn.org/2013/11/Bower-vs-npm/
On one hand npm was created to install modules used in a node.js environment, or development tools built using node.js such Karma, lint, minifiers and so on. npm can install modules locally in a project ( by default in node_modules ) or globally to be used by multiple projects. In large projects the way to specify dependencies is by creating a file called package.json which contains a list of dependencies. That list is recognized by npm when you run npm install, which then downloads and installs them for you.
On the other hand bower was created to manage your frontend dependencies. Libraries like jQuery, AngularJS, underscore, etc. Similar to npm it has a file in which you can specify a list of dependencies called bower.json. In this case your frontend dependencies are installed by running bower install which by default installs them in a folder called bower_components.
As you can see, although they perform a similar task they are targeted to a very different set of libraries.
For many people working with node.js, a major benefit of bower is for managing dependencies that are not javascript at all. If they are working with languages that compile to javascript, npm can be used to manage some of their dependencies. however, not all their dependencies are going to be node.js modules. Some of those that compile to javascript may have weird source language specific mangling that makes passing them around compiled to javascript an inelegant option when users are expecting source code.
Not everything in an npm package needs to be user-facing javascript, but for npm library packages, at least some of it should be.