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
Related
I've been working on a lot of different node.js projects. All of them have their own package.json file with their own needed packages. Every time I run node <mainfile>.js, npm installs all the packages to the project directory. Like so: C:/Users/me/Projects/<project-name>/node_modules.
This isn't a very big problem, but is there a way to make npm use/install to the global packages? Like in C:/Users/me/node_modules?
One of the advantages I could see this having is less storage being taken up, although it isn't a huge advantage.
I would assume that if it is possible, it would require you to add/modify something in the package.json file.
While looking into answers for this question, I've seen people saying that you should avoid installing packages globally. Can you also explain why this is a bad practice andy why I should avoid it?
Install Package Globally
NPM installs global packages into //local/lib/node_modules folder.
Apply -g in the install command to install package globally.
npm install -g express
To answer your other question
The obvious short answer is that your project depends on them. If your
project depends on a package, it should be documented in package.json
so that you can guarantee that it is installed when someone types npm
install. Otherwise, you’ll need to add extra steps in your README file
to inform anyone else who clones your project that they need to
install each of your global dependencies as well
Finally, even if someone installs the correct version of Browserify
for your project, they may be working on a different project that
requires a different version of that same tool, which would cause
conflicts. Several of your own projects might even use different
versions of Browserify because you updated it when you started a new
project and didn’t go back to make sure that earlier projects were
updated to work with the new version. These conflicts can be avoided.
You can only have one version installed globally. This causes problems if you have different projects that rely on different versions of a package.
Why not to install all packages globally
It's not really you shouldn't install a package globally it's more knowing what packages to install globally. The packages to install globally are ones that your project/application does not depend on.
How to identify a package that my project depends on
A package that your project is depended on is a package that your application could not run without like axios or express (an express API could not run without express installed or a web page that makes API requests with axios cant make those requests without axios) but something like http-server or minify is not needed to run the application so it can be installed globally.
Why is it important to have locally installed packages
It's important/good practice because if you are working with a group of developers or someone gets your work from Github they can just run npm install and get all the packages with out having to find all the packages them selfs.
How can I remove the node modules folder
You could technically globally install every package but I would sudjest not to. Node and many other developers know this is an issue that they have created a solution for in deno "the node killer".
I would recommend not installing all packages globally and if the node modules folder really annoys you try deno it fixes a lot of things that node developers hate.
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.
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.
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.
I have recently started playing with node.js, but I got lost in a big mess of different versions of node, npm, nvm and other packages. I don't know what is installed globally and what is installed locally (and if locally, how do the packages know which versions of node they can use?).
I'd like to have some summary of what different installation options do. In specific:
Where is node installed when I use nvm, apt-get, make install or when using other ways?
Is it a good idea to install node locally?
Why does nvm change my ~/.profile instead of installing itself in some system-recognizable bin folder?
I saw that nvm can install different versions of node alongside each other - why would I want to do this? I can install them locally instead, right?
Where does npm install packages? I saw that it checks packages aganist version of Node, what happens to these packages when node is upgraded?
In what cases it is better to use global or local installation? Where should I put my packages then (and where they put by default?)
What's the difference between npm, nvm and nave?
EDIT: There is a lot of ways to install node here, this makes me even more confused...
Where is node installed when I use nvm, apt-get, make install or when
using other ways?
apt-get installs all the software, not only node, on the file system following the Ubuntu convention where to store binaries, man files, shared files, logs, etc. However, using apt-get you'll have only the certain version of node which is determined by the distribution release cycle. If there are updates available they will be installed with apt-get update; apt-get upgrade However, the newest version of some app won't be available until it makes its way into the distribution. For example node v0.x.y might not be available until Ubuntu 13.10 the only way to get will be to install it manually. The good side of apt-get or other system package manager is that it manages updates and package removal for you. It stores all the data about the software package in it's own database. You can always delete the node with apt-get remove node and that's it.
make install install the package manually, but it is considered harmful. Never use the make install mainly because you won't be able to delete the package easily, you'll have to read the Makefile and manually delete all the files installed by it. In a situation where you want to use make install there is always checkinstall available. It's a software which creates a native package and registers it with the system. When you decide to delete the package you could do this with one command instead of many. wiki link; Ubuntu guide on checkinstall
Now nvm script is a node version manager. It is very helpful and easy to use. It allows you to have multiple versions of node to be installed and used in parallel on your machine. It doesn't compile the node from source like make install so it is very fast. it doesn't depend on your distribution release cycle so you have access to all the node versions available at the moment. nvm downloads precompiled binaries and is perfect for general use. It stores it's node files in it's own folder locally so in case you want to compare something between the different node versions it's easy to do.
Is it a good idea to install node locally?
If by locally you mean using nvm then it's very good for development, and testing. Not sure about production performance implications and benefits between having it's installed from source or using the nvm precompiled binaries. I use nvm for development and installed from source in production. However if someone could explain this issue any further I'll be glad to learn more.
Why does nvm change my ~/.profile instead of installing itself in some system-recognizable bin folder?
Because nvm isn't an executable. It is a set of bash functions which are sourced by shell and could be used separately. You can invoke nvm_ls and nvm_ls_remote and others without the main script after is is sourced into your shell. What the main script does it parses the command line arguments and pretty prints the output in case of for example `nvm_ls_remote'.
in the ~/.profile the following line is added
[[ -s /home/USERNAME/.nvm/nvm.sh ]] && . /home/USERANME/.nvm/nvm.sh # This loads NVM
loads all the functions into your shell
I saw that nvm can install different versions of node alongside each other - why would I want to do this? I can install them locally instead, right?
You can install them locally using make install or checkinstall but you will have to make aliases for them like node_0.8.1, node_0.8.2, node_0.10.1 , etc. AND you'll have to manage new aliases, installing all the packages, removing them in case you don't need them YOURSELF. These are a tedious and boring tasks which could be error prone sometimes. nvm does all of these tasks for you for free.
You want to do this to test your app under the different versions of node. For example you are good and tested under the v0.8 but you want to use the new features of the v0.10.3 how do you do that ? You have to download the source code, compile, make an alias and run your app. you could do this with just nvm install 0.10.3 and run your app.
Sometimes you have to support more than one version of node. For example some hosted environments are not keeping in touch with the latest release and only have v0.6 Your clients which use your server app might encounter a bug specific to this version. When you fix the bug you have to reproduce it first. Using nvm installation of the v0.6 is one line and half a minute. And you can check all the versions you want this way easily. Test your code under different versions and make sure you are good to go.
Where does npm install packages? I saw that it checks packages aganist version of Node, what happens to these packages when node is upgraded?
If you are using nvm the packages which are installed globally with -g option are tied to the relevant node version. When you switch between versions with nvm use 0.x you have to either install the packages again or use nvm copy-packages <version> to use the packages from in the current version. If the packages are installed locally then it depends. package.json should contain info on the dependencies of the app. If it says node: '0.8' and you just updated to 0.9 you might encounter troubles. For example the behavior of process.nextTick was changed in the latest releases compared to 0.6. So be careful.
In what cases it is better to use global or local installation? Where should I put my packages then (and where they put by default?)
It depends. For development nvm is superior in my opinion. For me it is convenient and simple. For production there are might be some performance implications when using the precompiled binary files not optimized for your system. It would be better to ask this as a separate question so the people with the relevant experience could answer.
What's the difference between npm, nvm and nave?
npm is a node package manager -> link It contains userland packages developed by other people. These packages are not part of the node core. npm is used for publishing your code and dependency management. If your app requires other app developed by other people it is convenient to publish it via npm.
nvm is a node version manager it does a completely separate thing. It gives you an ability to very easily switch between node versions on the same machine and manages all he changes in your $PATH environment variable.
Consider nvm as update manager for the Operation System and npm as a manager of the applications for this system. Well, this comparison isn't precise but just came upon my mind
nave is basically the same as nvm but it is an executable whereas nvm is a script which is sourced into the shell. Each system has it's own benefits. You could make a separate question regarding it's use cases and differences.
My answer isn't 100% complete and contains a lot of subjective personal opinions. However, I hope I'll at least make some points more clear so you might proceed with other more specific questions. Btw, this question list of yours could be asked as separate questions. I believe stackoverflow gives best results when specific questions are asked separately and more people with relevant experience could contribute.
If you run
npm install
in folder with package.json, it installs all packages localy (in the current folder).
Also, npm default install packeges local. To install it globaly - use -g flag:
npm install -g <package>
Execute next command:
npm config list
You see all npm config description.
You can install modules in the local context of your application with
npm install modulename
In this case the module will be installed to your node_modules folder of your application.
Otherwise you can install a module in the global context with
npm install -g modulename
In this case the module will be installed for the hole system environment usually at /usr/local/bin/modulename.
The global installation makes sense for modules you need in more than one application, like express or node-inspector.