Develop Reference

Including/bundling dependencies in npm library with webpack

I've used webpack for a few single page apps and am now trying to build an npm library to be used by some of those apps (and anyone else who might find it useful.)
I understand that peerDependencies in package.json and externals in the webpack config go together. If I'm writing an AngularJS plugin, I don't bundle angular, because the consumer should already have it installed and we want to work with whatever version they're using.
Where I'm confused is on how to include another library I don't expect the consumer to have. If I list it in dependencies and import it and don't include it in externals, webpack seems to bundle the other library with my code. I don't think this is what I want.
If I list it in dependencies and do include it in externals, it seems not to be available in the consumer unless I explicitly include it in the consumer, e.g. a script tag pointing to a CDN. It acts like a peerDependency, even though it isn't.
Is it possible to have have my library's dependencies installed by npm in the consumer app and available at runtime without a) bundling the dependency into my library or b) forcing consumers of the library to explicitly load an obscure package?

Publish Aurelia component on NPM?

We have built a small-ish application using Aurelia, and would like to be able to integrate the app into a larger codebase. For example, it may be desirable to publish the Aurelia app on NPM, so other projects could integrate our code.
How can we build/publish the Aurelia app, so that it can be instantiated in a larger JavaScript application?

Typically, you wouldn't publish an entire Aurelia application to NPM, rather you would push plugins to NPM.
The simplest way to learn how to do this is to follow the example of the various Aurelia repos. We build the code in to multiple formats, but the most important are AMD and CommonJS (which is more important for your company is dependent on what tooling your company is using). Once you've built the code, the next step is to make sure your package.json file is set up correctly. It's best to copy the example of what we're doing in our own repos.
I would start by looking at either the dialog plugin or the templating-resources plugin. Both of these show good examples of how to publish your Aurelia plugin to NPM, whether it is a public or private npm feed.
https://github.com/aurelia/dialog/blob/master/package.json
https://github.com/aurelia/templating-resources/blob/master/package.json
Both of these plugins are set up to support Webpack, JSPM/SystemJS, and the Aurelia CLI out of the box.

I totally agree with #Ashley in not publishing larger applications to the global NPM registry. The big advantage of it is the simplicity of all that small packages which can be used to build large applications.
If you feel you got some reusable code, put in an own package and publish it.
Anyway, to give you an answer which does not require you to publish your complete app: you can include a complete repository (which is probobly what you are lookig for) in a different application via NPM.
npm install git://github.com/somegit/hubrepo.git
Or directly via the package.json:
"dependencies": {
"private-repo": "git+ssh://git#github.com:somegit/hubrepo.git#v1.0.0",
}
You can also do something similiar e.g. using JSPM. This would be simply:
jspm install your-app=github:OrgOrUser/your-app#your-branch
If you are facing long relative paths in your imports now, depending on your tooling, you may be interested in something like e.g. Resolving require paths with webpack which shows how to alias relative paths.
Sources/Links:
How to install a private NPM module without my own registry?
npm install private github repositories by dependency in package.json

Do I need to keep a copy of js library in lib or vendor folder though already installed using npm?

Question 1 :
I am installing my project dependency libraries using npm and it gets stored in the npm_modules folder. Is it necessary to keep the copy of library like angular.js,angular-route.js in lib folder or vendor folder? I could see few people are using lib folder or vendor folders to store the library in the permanent manner. I am confused by seeing this.
Question 2:
Do I need to copy/paste the node_modules folder to production or just run the npm install command on the project folder's command prompt to install all the dependencies in production. How does a dependency library get promoted to production?
Thank you kindly for your advice.

It all depends on how you need to deploy your site to production, really. Ultimately, you will probably want to bundle all your JS files into one or a few files, which are minified and sent with gzip compression.
How you bundle them is up to you. There are quite a few options:
Browserify
Webpack
Grunt / gulp build process
And many more besides
As to whether you need to keep a copy of these bundled javascript files under version control, well I think that boils down to 1 key question: can you run a build process (such as one of the tools using NodeJS) on the production server, or on a build server that creates a zip file or installer? If so, then you don't need to include them, just get the build server or production server to check out the latest copy from version control, npm install and then run the build process.
But if the best you could do is have the production server check files out from source control, then you would want to include the final versions of the files to use in the repository.
Keeping generated files, such as your bundled javascript files, in your source control repo should be avoided where possible. Because otherwise, every commit has to contain the changes to the source files, and the corresponding change to the generated files as well. And the latter is just noise, and has to be ignored by every developer looking at a diff/patch for a commit.

Creating bower projects that have dependencies

I am creating a javascript client side library which I will make available via Bower and depends on two other libraries, one that is available via Bower (https://github.com/abritinthebay/datejs) and another that is available only via npm (https://github.com/fent/randexp.js). I am concerned about how the users of my library would go about using it. My doubts and fears are:
how can I declare the second library as a dependency of my library when it's only available via npm?
after the user installs my library, will he/she have to be aware of the dependencies and manually include the corresponding javascript files in their index.html? I am aware of grunt-bower-install solving this issue, but I'm concerned about people who don't even use grunt at all.
would it be so bad if I just gave up on all of this and included the code of said libraries in my own code?
(bonus round): I want my library to be available as an AngularJS service, as a node.js module, and as a 'normal' javascript function. Is there a way for me to achieve this using only one repository or do I have to create 3 separate projects?

1) You need to wrap the second library in a bower package if you want it to be available to the bower package management system. npm is something entirely different and you won't be sharing between the two directly.
2) Yes, the user needs to ensure the dependencies are loaded in the right order on each page. Bower just ensures your dependencies are installed and at the correct version.
3) Generally, I'd avoid this. They're separate projects with orthogonal concerns. This is why we've created package managers like bower to begin with.
Bonus:
4) Yes, you can achieve this with one repository. Each package management service requires their own configuration files - but there's nothing wrong with having a bower.json and a package.json both sitting at the root of your repository. You just use npm and bower separately and respectively to publish to each system.
PS. This should have been more than 1 question.

What is the difference between Bower and npm?

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.