When installing packages using nodejs, what happens if you run the same command multiple times, i.e. "npm install -g cordova ionic"?
Does this cause problems/issues? Or does it automatically recognize that you have it installed and nothing really happens? Thanks.
Usually nothing of note, but it simply "installs what you tell it to". npm installs to ./node_modules relative to where you run it, and installs whatever version is specified, or "the latest one" if you don't specify any version. If there is already a dependency dir for what you're installing, that's deleted, and then the thing you're telling npm to install is put in its place.
Does that cause problems? Only if you let it. If it deletes and reinstalls, the net effect is no change. If it deletes a specific version and replaces it with a different version, then that might be a problem, but a problem of your own making: this is what the package.json dependencies list is for, so that npm install installs exactly what you need it to.
Related
I always thought that you should initialize npm first before installing any packages
npm init --yes
However I found out that I could just go straight to installing packages
npm i example-package
Then the package would be installed and package.json would be created at the same time.
Is there any reason I should be doing npm init first? Is it only required if I want to specify project details?
It is not required. You can install packages without, and everything will work.
npm init can do basically two things:
ask for basic project info to include in packages.json
create a specific type of project (for example React) by using npm init typeofproject
If you just want to use packages and don’t care about naming the project or using a template, just install packages.
npm init is there when you are installing the project very first time.
else you don't need to use npm init for installing any package
Well, kind of a late answer, but as far as I know (correct me if im wrong), one of the features is it gets set up with package.json which includes the dependencies list. That way, NPM can simply install the packages on the list (via the "npm init" if you have a situation that you want to clone the app into another machine), rather than copy pasting the whole project folder.
This isn't a direct answer to the question, but, if sheds some light at some point, why not.
I'm trying to set up a development environment with several packages, and as a result I need to manually install some dependencies. More specifically, I have some local changes in several packages which I need to test before I can push them to github, so I can't just npm install the top level because it won't pick up those change. So I run the first npm install manually on packages which are missing, and then try to run my node code and see which package it is still missing, then try to npm install what it says is missing.
However, when I go to install the second package, it ends up with this message:
added 3 packages from 4 contributors, removed 799 packages and audited 3 packages in 4.197s
The second install removed practically every package that was already installed! I didn't notice this until about the third time, when I realized that I seemed to be installing the same thing over and over.
However can I prevent this particularly naughty behavior and force npm to only install what I tell it to and leave everything else alone?
Have a look at npm link if you need to test against modified packages.
From npm link:
This is handy for installing your own stuff, so that you can work on it and test it iteratively without having to continually rebuild.
Say b is a dependency of a. You made changes to b and want to check if a still works with those changes. Instead of using b in node_modules installed from npm, use your local, modified version:
cd ~/projects/b # go into the package directory
npm link # creates global link
cd ~/projects/a # go into some other package directory.
npm link b # link-install the package
Now, any changes to ~/projects/b will be reflected in ~/projects/a/node_modules/b/.
If your development flow involves updating in parallel packages which depend on one another, you might consider switching your project's package manager to from npm to yarn to take advantage of yarn's workspaces feature.
Yarns's workspaces allow you to easily setup a single monorepo containing all your interconnected dependencies, and let yarn thinking how to link them together in your dev environment.
i had a similar problem today , & thought this might help someone in the future and l have found out that if you install simultaneouly it
npm install --save package1 package2 package3 ...
it worked as l had
npm install xlsx angular-oauth2-oidc
but if you install separately it will have issues
Edit 2 More infor by #Michael
installing multiple packages in the same command also prevents hooks from being installed multiple times
Remove "package-lock.json" file befor installing the new package.
Are you saving the dependencies to package.json?
To Save : npm install --save {package_name}. This will save the package to package.json and install using npm install.
You can't particularly control the dependencies(fully). The dependencies which you have installed might be using dependencies themselves.So when you remove a package, npm deletes all the package's dependencies and the package.
I have an Electron app that I'm trying to install node modules for. When I run npm install, it creates the node_modules folder but all the modules go into a subfolder called .staging. Each module also has -xxxxx appended to it, where the x's are some random alphanumerics.
Other Electron apps I've created have never done this. All the node modules sit in the root of node_modules and don't have -xxxxx appended.
Any idea why this is happening?
I was also facing the same issue, I tried the steps below:
Delete package-lock.json
Delete Node Modules folder
Try installing it using below command (should be in open network)
npm install
Note: - ".staging" means, those dependencies are getting downloaded so for the temporary basis it keeps all those dependencies under ".staging" folder. Once all gets downloaded properly then it will showcase them under node_modules only.
I hope this will work.
This only happens temporarily until the modules are downloaded and installed. Node seems to do this so it can place together common submodules from all the modules you are installing so it can better structure the node modules folder(mainly for windows users).
If this is happening after an npm install finishes it is likely that there is something wrong with your node installation or something in the install failed.
If you're automatically installing node_modules using CI/CD you should check out npm ci. Also check out this Stackoverflow question.
npm ci
The documentation points out the differences between npm install and npm ci.
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. This is nice, because it prevents having to do something like rm -rf node_modules.
It will never write to package.json or any of the package-locks: installs are essentially frozen.
.staging is a temporary npm folder, where the modules are temporarily saved while they are being downloaded, if the package.json downloads are still not completed, the created folder remains, until the installation is complete.
The problem may be lack of space on your hard drive.
I was having 2 versions of node installed on my system.
nodejs v4.2 and node v8.6
I thought this could be conflicting, so I deleted nodejs v4.2 with following commands.
sudo apt-get remove nodejs
and linked the path with
sudo ln -s /usr/bin/node /usr/bin/nodejs
Again I ran npm install and it got fixed
Delete package.lock.json
Delete node_modules
run npm update
This worked for me
I moved the project from C drive to other drive and ran the following commands
take a backup of older node modules if you are running this and existing project
npm cache clean --force
npm update
I faced similar issue and tried the above answers but it did'nt worked for me;
I followed below steps to resolve this issue-
1.npm audit
By running npm audit I got list of pending packages to install-
2.npm i packagename
After installing one or two package one by one from list, I used
3.npm install
At this time the installation went smooth without any lag or hangup. Hope this help who is facing similar issue :).
Sometimes the cache is corrupt and also unremovable.
This fixed the issue I was experiencing.
If you are using nvm
Get the current node version node --version
nvm uninstall (that version)
nvm install (that version)
nvm use
npm install
If you have a windows machine where you do not posses Admin rights to it.
Try deleting node_modules and install using 'npm install' from command line as
'ADMINISTRATOR'
It works!
Anyways, it comes down to an open network thing ;)
I just setup a test, and tried to npm install express even though express already exists globally on my system. To my surprise, instead of using the global version, it ended up re-installing a version locally!? Isn't it supposed to use the global version... Or am I suppose to use -g every time, even when I only want to use the existing global version. Otherwise, what's the point of installing anything locally!?
The answer is "NO". It isn't supposed to use your global version.
If you want to use your global version, then you doesn't need to execute npm install at all because it is already installed.
If you do it then, obviously, you are saying "I want to install it locally to my project". And more than that: "I want to install its latest version unless it is declared in my package.json with other explicitly specified version".
In fact, the actual question is: Why in the hell would you want to not install a dependency of your project locally? To have more version mismatch issues?
As #anshuman_singh says, best practice is to always do an npm install --save.
You are able to use globally installed packages, of course. It could be handy for fast testing code that you will drop just after a few hours or so.
But, anyway: If you doesn't have really hard disk or network bandwidth issues, installing all dependencies locally will avoid you too much trouble in the future.
On the other hand, uploading that modules to your code repository is also a bad idea (maybe that is what you were trying to avoid) because, with different versions of node, most native modules won't work if not rebuild. But most VCS support ignoring files and or directories that must not be uploaded.
For example, in git (.gitignore file):
**/node_modules
In summary:
npm init (if you didn't already it).
npm install --save for all your project dependencies.
npm install --save-dev for dependencies not needed in production (testing stuff).
Don't upload node_modules to your VCS.
After new checkout: npm install or npm install --production (to not install dev-dependencies).
npm install -g only for tools you will use in console.
This way, you are sure that you will have in production (or other dev environments) the exact same version of each package.
And, finally, if you ever want to upgrade some package to its latest version, simply run:
npm install --save <pagkage_name>#latest.
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.
The first option is the best in my opinion. Simple, clear, explicit. The second is really handy if you are going to re-use the same library in a bunch of different projects
Install locally-
npm install moduleName
install locally and save in package.json-
npm install moduleName --save
install globally-
npm install moduleName -g
this is a very newbie question. But I really cannot figure it out through Google search.
I want to understand what happens when one executes
sudo npm install -g "node module name"
I understand that the right module will be installed to, normally, /usr/local/....
However, why would this be available globally?
For example, I installed node-inspector locally in my project. But my shell does not understand when I type "node-inspector".
But once I install it globally,
node-inspector &
command will does the right thing for me.
I really want to understand how this happens.
Thanks
Quoting the npm's doc:
Local install (default): puts stuff in ./node_modules of the current
package root.
Global install (with -g): puts stuff in /usr/local or
wherever node is installed.
Install it locally if you're going to
require() it.
Install it globally if you're going to run it on the
command line.
If you need both, then install it in both places, or use
npm link.
It's quite a short description (which, I suppose, is still enough to see the difference), but the linked page describes the whole process of installing modules with npm in more details. )