I am studying about npm and I have some questions.
Where the npm get the package from? i.e. when run npm install <package-name> or yarn add <package-name>.
When get the package, do npm get the package as raw or get then build it(like run the build script written in package.json)?
When publish the package, the repository field of package.json is required?
Can be different between the repository for publishing and the repository in pacakge.json?
To answer your questions:
npm gets them from the NPM package registry, and so does yarn, but Yarn probably has a proxy registry in front of it. In general, you can say, both tools fetch their packages from https://npmjs.com by default.
It gets the package as it was published (so, in short, the answer is "raw"). Building is up to the publisher and depends on the type of package. Often, some prepublish task builds something into dist/ (or any other location in the package), and these files are also shipped with the package others then download. Building rarely happens after installing a package (exception here are library-wrapping packages built with node-gyp).
The repository field is not required, to my knowledge, but it is good practise to include it (it will be displayed on the NPM website, for example).
Technically, yes. You can just specify any repository in repository, but it wouldn't make much sense to specify one that isn't the source of the package.
If you in general want to read up more on how npm works, check out it's documentation over at https://docs.npmjs.com/
I'm working with continuous integration and discovered the npm ci command.
I can't figure what the advantages are of using this command for my workflow.
Is it faster? Does it make the test harder, okay, and after?
From the official documentation for npm ci:
In short, the main differences between using npm install and npm ci are:
The project must have an existing package-lock.json or npm-shrinkwrap.json.
If dependencies in the package lock do not match those in package.json, npm ci will exit with an error, instead of updating the package lock.
npm ci can only install entire projects at a time: individual dependencies cannot be added with this command.
If a node_modules is already present, it will be automatically removed before npm ci begins its install.
It will never write to package.json or any of the package-locks: installs are essentially frozen.
Essentially,
npm install reads package.json to create a list of dependencies and uses package-lock.json to inform which versions of these dependencies to install. If a dependency is not in package-lock.json it will be added by npm install.
npm ci (also known as Clean Install) is meant to be used in automated environments — such as test platforms, continuous integration, and deployment — or, any situation where you want to make sure you're doing a clean install of your dependencies.
It installs dependencies directly from package-lock.json and uses package.json only to validate that there are no mismatched versions. If any dependencies are missing or have incompatible versions, it will throw an error.
Use npm install to add new dependencies, and to update dependencies on a project. Usually, you would use it during development after pulling changes that update the list of dependencies but it may be a good idea to use npm ci in this case.
Use npm ci if you need a deterministic, repeatable build. For example during continuous integration, automated jobs, etc. and when installing dependencies for the first time, instead of npm install.
npm install
Installs a package and all its dependencies.
Dependencies are driven by npm-shrinkwrap.json and package-lock.json (in that order).
without arguments: installs dependencies of a local module.
Can install global packages.
Will install any missing dependencies in node_modules.
It may write to package.json or package-lock.json.
When used with an argument (npm i packagename) it may write to package.json to add or update the dependency.
when used without arguments, (npm i) it may write to package-lock.json to lock down the version of some dependencies if they are not already in this file.
npm ci
Requires at least npm v5.7.1.
Requires package-lock.json or npm-shrinkwrap.json to be present.
Throws an error if dependencies from these two files don't match package.json.
Removes node_modules and install all dependencies at once.
It never writes to package.json or package-lock.json.
Algorithm
While npm ci generates the entire dependency tree from package-lock.json or npm-shrinkwrap.json, npm install updates the contents of node_modules using the following algorithm (source):
load the existing node_modules tree from disk
clone the tree
fetch the package.json and assorted metadata and add it to the clone
walk the clone and add any missing dependencies
dependencies will be added as close to the top as is possible
without breaking any other modules
compare the original tree with the cloned tree and make a list of
actions to take to convert one to the other
execute all of the actions, deepest first
kinds of actions are install, update, remove and move
npm ci will delete any existing node_modules folder and relies on the package-lock.json file to install the specific version of each package. It is significantly faster than npm install because it skips some features. Its clean state install is great for ci/cd pipelines and docker builds! You also use it to install everything all at once and not specific packages.
While everyone else has answered the technical differences none explain in what situations to use both.
You should use them in different situations.
npm install is great for development and in the CI when you want to cache the node_modules directory.
When to use this? You can do this if you are making a package for other people to use (you do NOT include node_modules in such a release). Regarding the caching, be careful, if you plan to support different versions of Node.js remember that node_modules might have to be reinstalled due to differences between the Node.js runtime requirements. If you wish to stick to one version, stick to the latest LTS.
npm ci should be used when you are to test and release a production application (a final product, not to be used by other packages) since it is important that you have the installation be as deterministic as possible, this install will take longer but will ultimately make your application more reliable (you do include node_modules in such a release). Stick with LTS version of Node.js.
npm i and npm ci both utilize the npm cache if it exists, this cache lives normally at ~/.npm.
Also, npm ci respects the package-lock.json file. Unlike npm install, which rewrites the file and always installs new versions.
Bonus: You could mix them depending on how complex you want to make it. On feature branches in git you could cache the node_modules to increase your teams productivity and on the merge request and master branches rely on npm ci for a deterministic outcome.
The documentation you linked had the summary:
In short, the main differences between using npm install and npm ci are:
The project must have an existing package-lock.json or npm-shrinkwrap.json.
If dependencies in the package lock do not match those in package.json, npm ci will exit with an error, instead of updating the package lock.
npm ci can only install entire projects at a time: individual dependencies cannot be added with this command.
If a node_modules is already present, it will be automatically removed before npm ci begins its install.
It will never write to package.json or any of the package-locks: installs are essentially frozen.
The commands are very similar in functionality however the difference is in the approach taken to install the dependencies specified in your package.json and package-lock.json files.
npm ci performs a clean install of all the dependencies of your app whereas npm install may skip some installations if they already exist on the system. A problem may arise if the version already installed on the system isn't the one your package.json intended to install i.e. the installed version is different from the 'required' version.
Other differences would be that npm ci never touches your package*.json files. It will stop installation and show an error if the dependency versions do not match in the package.json and package-lock.json files.
You can read a much better explanation from the official docs here.
Additionally, you may want to read about package locks here.
It is worth having in mind that light node docker images like alpine do not have Python installed which is a dependency of node-gyp which is used by npm ci.
I think it's a bit opinionated that in order to have npm ci working you need to install Python as dependency in your build.
More info here Docker and npm - gyp ERR! not ok
npm ci - install exactly what is listed in package-lock.json
npm install - without changing any versions in package.json, use package.json to create/update package-lock.json, then install exactly what is listed in package-lock.json
npm update - update package.json packages to latest versions, then use package.json to create/update package-lock.json, then install exactly what is listed in package-lock.json
Or said a different way, npm ci changes 0 package files, npm install changes 1 package file, and npm update changes 2 package files.
It does a clean install, use it in situations where you would delete node_modules and re-run npm i.
I have no idea why some people think it's short for "continuous integration". There is an npm install command that can be run as npm i and an npm clean-install command that can be run as npm ci.
npm install is the command used to install the dependencies listed in a project's package.json file, while npm ci is a command that installs dependencies from a package-lock.json or npm-shrinkwrap.json file. The npm ci command is typically used in continuous integration (CI) environments, where the package-lock.json or npm-shrinkwrap.json file is checked into version control and should not be modified. Because npm ci installs dependencies from a locked file, it is a faster and more reliable way to install dependencies than npm install, which could install different versions of dependencies based on the state of the package.json file.
I have 2 projects(packages) in npm, I want to inject package_A as dependency to package_B. In package_A root folder, I run npm install -g, then npm install it to C:\Users\Myuser\AppData\Roaming\npm\node_moduls\package_A folder. Now in packages.json in package_B I add "package_A": "1.0.0" in dependencies. When in package_B root file I run npm install, its failed package_A#1.0.0 not found.
How can I identified npm to its my own local package?
Notes:
We are a team, then I don't want to address package_A explicitly.
We are using nexus repository manager.
I don't want to publish my projects to http://registry.npmjs.org/.
I'm not 100% clear what you have tried. If you are going to use a custom module for another application you are developing, installing globally won't do the trick. You have to publish that module in npm.
Check this link for more info on publishing in npm
If you have completed the steps correctly, and still no good happens, please check your naming of the module in package.json file.
Instead of typing in the name and version number in package.json file and then npm install, try directly installing in the terminal with --save so that it will automatically be added to package.json file with correct spelling.
Before publishing my node library, I could use the advice the npm documentation wrote about:
To test a local install, go into some other folder, and then do:
cd ../some-other-folder
npm install ../my-package
Prior to version 5 of npm, I had no problem as it produce what I expected, ie a folder with the output of what I will publish.
However, using npm 5, it now creates a symlink to my local project as described in the npm documentation:
npm install :
Install the package in the directory as a symlink in the current
project. Its dependencies will be installed before it's linked. If
sits inside the root of your project, its dependencies may be
hoisted to the toplevel node_modules as they would for other types of
dependencies.
How can I use the "old" way to install local project? Or is there a new way to check if my library is correct?
Thank you.
Use npm pack + npm install (as suggested by install-local package)
npm pack <path-to-local-package>
npm install <package-version.tgz>
This will effectively copy your local package to node_modules.
Note that this will package only production relevant files (those listed in the files section of your package.json). So, you can install it in a test app under the package own directory. Something like this:
my-package
package.json
test
test-app
package.json
node_modules
my-package
Assuming that test dir is not included in the files in my-package/package.json.
This works the same way with npm 5 and older versions.
I wrote npm-install-offline which allows you to install npm packages from a local repository or folder. By default it copies the folder on install but you can also choose to symlink.
https://www.npmjs.com/package/npm-install-offline
npx npm-install-offline ../some-package
Or
npx npm-install-offline my-npm-package --repo ./my-offline-npm
It also will install the package dependencies which npm does not do with local packages.
I've been tasked with removing bower where possible and instead using NPM to install modules. I've done a search of the codebase and the only bower.json files are within NPM node modules. I thought that NPM was an alternative to bower, is this incorrect?
I was expecting to find a bower.json file in the project root. As I haven't does it should like NPM is already being used instead?
You can use NPM as an alternative to bower, yes.
Every module has a bower.json because the module wants to support bower and npm as well. Module managers can write stuff like version number, ignore certain files to download, etc. You don't need to worry about these files.
Your package doesn't have a bower.json - perfect. You don't support bower.