When and why should I install node modules globally and locally? Why many manuals have "npm install -g" while other do not? Is this project or OS specific?
Taken from an official node.js blog:
In general, the rule of thumb is:
1) If you’re installing something that you want to use in your
program, using require('whatever'), then install it locally, at the
root of your project.
2) If you’re installing something that you want to use in your shell,
on the command line or something, install it globally, so that its
binaries end up in your PATH environment variable.
Related
I'm new to NodeJS and I'm having trouble understanding npm
I'm following this tutorial and I can't seem to map the concepts tot he ones I know from my Django experience.
Where exactly do my packages get installed? Can't I have project-specific packages like Django does with virtualenv? If I understand correctly this might cause compatibility issues in the future.
npm is like pip in Python, its a way to download and install packages. node_modules is a directory where these packages are installed. This is not the same as a virtual environment; which has the interpreter along with additional libraries.
In node, you can get a virtual environment (see: is there an virtual environment for node.js? for more details). The idea is the same - an isolated environment for better testing and portability.
In Python, there is requirements.txt (and pipenv), in node you have package.json (for packages), and modules (which go in node_modules).
The documentation goes into a bit more detail into the difference of these; but coming from Python you can think of a node package as something that has a package.json (so, like a setup.py), and a module is just any file you can import (or include() in node).
Hey when you install a package with npm the packages are installed to node_modules within the working directory (on a project to project basis).
With the exception of when installing packages globally (npm install -g packagename)
To add to the excellent answer above, and to confirm if this suspicion of mine is true:
The major difference between node_modules not creating a true virtual environment is that whenever you run a node application, it will "reach_out" to use the node/js interpreter that is installed "globally" .. this of course can be manipulated with nVm, but python's virtual environments don't run on a "globally" installed python interpreter, instead with the one scoped-narrowly to the virtual environment
What is the difference between installing a package locally and globally using npm?
From my understanding:
Locally install: npm install <package>
This package/module will find on your local node_modules folder and
can only be usable for this project.
This package/module can be accessible in using require("package")
from code.
This package/module can't be accessible in command line interface.
Globally install: npm install <package> -g
This package/module will find on where node is installed in your machine like /usr/local and can be usable everywhere.
This package/module can't be accessible in using require("package")
from code.
This package/module can be accessible in command line interface.
Please let me know. If I could misunderstand anything here. Thanks!
You are correct except for 1 point.
The local packages exposing CLI utilities can be accessed from the command line. Newer versions of NPM create this .bin/ directory inside the local node_modules/.
Whenever you try to use a tool (let's take babel for example), if you use it from the command line and you have it installed in your project, npm will properly identify that package and run it's CLI for you.
Here's a useful article on the topic.
http://www.2ality.com/2016/01/locally-installed-npm-executables.html
Global modules are mostly tools like gulp, yoman or any other module you use in your daily work.
Local modules are the dependencies of your project. You should never depend on a global module in your project. Even dependencies as gulp should be a local dependency in your dev-dependency section.
I have nodejs installed on a MBP which runs OSX 10.9, I have installed as a package downloaded from the nodejs website. Then I have installed the MEAN stack following instructions on mean.io.
The commands are:
sudo npm install -g mean-cli
mean init yourNewApp
That works correctly
Now the real issue is when after my app is created I enter the dir using the terminal, and write gulp, and it thows me some errors that some mandatory modules are not found.
The modules are written in the package.json file that mean generated, and they are installed as global modules on ~/.npm
I browsed the folder and there are all the required packages folders, inside the folders there is a package.tgz file which has the code of the package and a package folder which holds a package.json file describing the package itself.
Now I don't understand why the packages are compressed and why if they are installed globaly can not be accessed from gulp on my project folder.
Thanks in advance.
If you install some global module then you better don't put it into the package.json of your app because when you run your app that's the first place where is going to search and if it is there your app is going to look at node_modules folder and if it is not there your app will crash.
My advice is try to install your modules inside your app, npm install your_module --save because your app is gonna be portable and with a simple npm install you will be able to install all your needed packages.
But if you still wanna install global packages you maybe wanna follow this rules:
If you’re installing something that you want to use in your program, using require('whatever'), then install it locally, at the root of your project.
If you’re installing something that you want to use in your shell, on the command line or something, install it globally, so that its binaries end up in your PATH environment variable.
If you have the time to read the link then you will see that there are exceptions and how to handle them.
In my package.json file, I have bower listed as a dependency. After I run npm install, bower gets installed locally. When I try to run bower after installing it locally I get an error
"bower" is not recognized as an internal or external command
It seems the only way to resolve this is to install bower globally. Why should I have to do this? If my project contains a local copy of bower, why won't node use it?
Installing locally makes bower available to the current project (where it stores all of the node modules in node_modules). This is usually only good for using a module like so var module = require('module'); It will not be available as a command that the shell can resolve until you install it globally npm install -g module where npm will install it in a place where your path variable will resolve this command.
Edit: This documentation explains it pretty thorougly.
You can execute your local instance by typing the line below in cmd:
node_modules/bower/bin/bower <bower args>
We use both PHP and JavaScript, so we have composer and npm.
Each of the projects we work on have different packages both for runtime of the package as well as build/dev tools.
As there are version constraints in each project, installing version x of a package globally (that would be run from the command line), would cause us issues, we install all the tooling in each package. Much easier to define in the appropriate composer.json / package.json files.
But running the CLI tools is a pain if you have to constantly add an additional path to the command.
To that end, we have recommend to the team that the following paths are added to your $PATH in the appropriate .bashrc (or equivalent):
./vendor/bin:./node_modules/.bin
(EDIT: For Windows, the paths would be .\vendor\bin;.\node_modules\.bin;)
So, whilst in project X, we have access to the CLI tools for that project. Switch to project Y, and we get that projects tools.
Sure, you are going to get duplications, but each project is maintained by different teams (and some people are in multiple teams), so again, having 1 version in the global setup is an issue there.
Usually you install NPM modules globally if you want them included in your path to be ran from the command line. Since it is installed locally you will have to run it from the node_modules folder.
I am trying to install Less from NPM by running npm install -g less in the command line. I checked the docs for the install command:
In global mode (ie, with -g or --global appended to the command), it
installs the current package context (ie, the current working
directory) as a global package.
What does it mean by "global package"?
You are not required to install Less globally.
Installing it locally means the module will be available only for a specific project (the directory you were in when you ran npm install), as it installs to the local node_modules folder.
A global install will instead put the module into your global package folder (OS dependent), and allows you to run the included executable commands from anywhere. Note that by default you can only require local packages in your code.
See the node.js docs for more info on global vs local packages.
Generally speaking, you should install most modules locally, unless they provide a CLI command that you want to use anywhere.
In the end, I suggest you install less globally, as less provides an executable command that you will likely need in different projects. This is also what the Less docs recommend.
From: https://nodejs.org/en/blog/npm/npm-1-0-global-vs-local-installation/
There are two ways to install npm packages:
globally —- This drops modules in {prefix}/lib/node_modules, and puts executable files in {prefix}/bin, where {prefix} is usually something like /usr/local. It also installs man pages in {prefix}/share/man, if they’re supplied.
locally —- This installs your package in the current working directory. Node modules go in ./node_modules, executables go in ./node_modules/.bin/, and man pages aren’t installed at all.
It simply means that the package you are installing while be available/integrated throughout your Nodejs platform.