I have two modules - my main project and a component library - where I want to link the lib to the main project. Both is working with webpack and react. So I did:
In comp-lib dir:
npm link
In project dir:
npm link comp-lib
The package is showing up in the node_modules folder, but when I work on the component library the changes are not reflected in main project. What am I missing out?
I couldn't really find something about this issue on Google and the npm link doc just says about the example: "Now, any changes to ~/projects/node-redis will be reflected in ~/projects/node-bloggy/node_modules/node-redis/."
Had similar problem with linked package - npm link dep was picking up old version of "dep".
Running npm link (again) in "dep" folder solved the problem. Theoretically it should be called only once, but for some reason it gets out of sync sometimes.
Thus in order to reliably update linked project, execute these steps after each change:
Rebuild linked project
run npm link
In host project run npm link dep
I don't remember exactly what problems I had and I am also not sure if all of that is necessary but for me it works great.
I added the following mini script to the package.json scripts list
"scripts": {
"clean": "if exist dist ( rd /S /Q dist)",
"updateLink": "npm run clean && tsc && npm rm my-lib -g && npm link"
}
(Replace "my-lib" with your package name)
Then simply call npm run updateLink whenever you change something in the lib.
What it does:
npm run clean deletes the dist folder. Useful if you have renamed files and the typecript compiler does not delete the old files but builds new ones in parallel
tsc to compile ts->js to the dist folder
npm rm my-lib -g && npm link to remove your lib and add it again from the global modules folder. I don't remember why I had to remove it first but it solved some problem I guess.
Make sure that the Node versions of the main project and dependency project match precisely.
If you use nvm to manage multiple projects on multiple node versions, the npm link will produce the symbolic link only in the node version that npm link was initiated from (i.e., the dependency project).
It might be that you bumped version on your component, and forgot to increase the version on your main project.
Then, any npm operation will download the version indicated in the package-lock.json: the outdated version, thus removing the link set up by npm link.
My issue was that my module/package in this case was exporting the build files. I didnt fix it because we export multiple files from multiple components but if you run into this issue, change main (and exports in my case) to whatever file exports your modules
"main": "./dist/shared-lib.umd.js",
"module": "./dist/shared-lib.es.js",
"exports": {
".": {
"import": "./dist/shared-lib.es.js",
"require": "./dist/shared-lib.umd.js"
},
"./style": "./dist/style.css"
}
I have some module in my node_module folder but because I am amateur in nodejs, when I wanted to install theme, I forgot to use --save with npm install.now I have lots of module but my package.json is empty so is there any way to add theme into package.json.
Sorry if my question is silly one I am beginner in nodejs
Simply change into the directory containing node_modules, backup any existing package.json in there, then use npm init to re-create the package.json.
The generated package.json will include any modules that already exist within node_modules.
Sample run:
$ cd /my/project
$ mv package.json package.json.bak # Backup package.json
$ npm init # Recreate package.json with dependencies populated
Already asked and well answered!
Here're different ways suggested to create / maintain package.json file
Is there a way to automatically build the package.json file for Node.js projects
Its simple. Edit the package.json file and add the following for development dependencies:
"devDependencies": {
"broccoli-asset-rev": "^2.0.2",
"broccoli-merge-trees": "^0.2.1",
"broccoli-svg-sprite": "^1.0.3",
......
}
To get a list of package names and version numbers, you may look at node_modules/module folder/package.json for each of the modules to pick up the official package name and version. It will be of the form:
{
"name": "<<name of the package>>",
"version": "2.1.0",
"description": "broccoli asset revisions (fingerprint)",
....
}
just copy the name and version information from above into devDependencies into your project's package.json and you should be good to go.
Also have a look here Is there a way to automatically build the package.json file for Node.js projects
and here: https://docs.npmjs.com/files/package.json
You can install the same package again using npm install --save <package> and it should just replace the current package files with freshly installed ones. It will also add the packages you already added with the default version notation.
What is the difference between:
npm install [package_name]
and:
npm install [package_name] --save
and:
npm install [package_name] --save-dev
What does this mean? And what is really the effect of --save and -dev keywords?
The difference between --save and --save-dev may not be immediately noticeable if you have tried them both on your own projects. So here are a few examples...
Let's say you were building an app that used the moment package to parse and display dates. Your app is a scheduler so it really needs this package to run, as in: cannot run without it. In this case you would use
npm install moment --save
This would create a new value in your package.json
"dependencies": {
...
"moment": "^2.17.1"
}
When you are developing, it really helps to use tools such as test suites and may need jasmine-core and karma. In this case you would use
npm install jasmine-core --save-dev
npm install karma --save-dev
This would also create a new value in your package.json
"devDependencies": {
...
"jasmine-core": "^2.5.2",
"karma": "^1.4.1",
}
You do not need the test suite to run the app in its normal state, so it is a --save-dev type dependency, nothing more. You can see how if you do not understand what is really happening, it is a bit hard to imagine.
Taken directly from NPM docs docs#dependencies
Dependencies
Dependencies are specified in a simple object that maps a package name
to a version range. The version range is a string that has one or
more space-separated descriptors. Dependencies can also be identified
with a tarball or git URL.
Please do not put test harnesses or transpilers in your dependencies
object. See devDependencies, below.
Even in the docs, it asks you to use --save-dev for modules such as test harnesses.
--save-dev is used to save the package for development purpose.
Example: unit tests, minification..
--save is used to save the
package required for the application to run.
By default, NPM simply installs a package under node_modules. When you're trying to install dependencies for your app/module, you would need to first install them, and then add them to the dependencies section of your package.json.
--save-dev adds the third-party package to the package's development dependencies. It won't be installed when someone runs npm install directly to install your package. It's typically only installed if someone clones your source repository first and then runs npm install in it.
--save adds the third-party package to the package's dependencies. It will be installed together with the package whenever someone runs npm install package.
Dev dependencies are those dependencies that are only needed for developing the package. That can include test runners, compilers, packagers, etc.
Both types of dependencies are stored in the package's package.json file. --save adds to dependencies, --save-dev adds to devDependencies
npm install documentation can be referred here.
--
Please note that --save is now the default option, since NPM 5. Therefore, it is not explicitly needed anymore. It is possible to run npm install without the --save to achieve the same result.
Let me give you an example,
You are a developer of a very SERIOUS npm library which uses different testing libraries to test the package.
Users download your library and want to use it in their code. Do they need to download your testing libraries as well? Maybe you use jest for testing and they use mocha. Do you want them to install jest as well? Just To run your library?
No. right? That's why they are in devDependencies.
When someone does, npm i yourPackage only the libraries required to RUN your library will be installed. Other libraries you used to bundle your code with or testing and mocking will not be installed because you put them in devDependencies. Pretty neat right?
So, Why do the developers need to expose the devDependancies?
Let's say your package is an open-source package and 100s of people are sending pull requests to your package. Then how they will test the package? They will git clone your repo and when they would do an npm i the dependencies as well as devDependencies.
Because they are not using your package. They are developing the package further, thus, in order to test your package they need to pass the existing test cases as well write new. So, they need to use your devDependencies which contain all the testing/building/mocking libraries that YOU used.
A perfect example of this is:
$ npm install typescript --save-dev
In this case, you'd want to have Typescript (a javascript-parseable coding language) available for development, but once the app is deployed, it is no longer necessary, as all of the code has been transpiled to javascript. As such, it would make no sense to include it in the published app. Indeed, it would only take up space and increase download times.
As suggested by #andreas-hultgren in this answer and according to the npm docs:
If someone is planning on downloading and using your module in their program, then they probably don't want or need to download and build the external test or documentation framework that you use.
However, for webapp development, Yeoman (a scaffolding tool that installs a peer-reviewed, pre-written package.json file amongst other things) places all packages in devDependencies and nothing in dependencies, so it appears that the use of --save-dev is a safe bet in webapp development, at least.
--save-dev saves semver spec into "devDependencies" array in your package descriptor file, --save saves it into "dependencies" instead.
--save-dev is used for modules used in development of the application,not require while running it in production environment
--save is used to add it in package.json and it is required for running of the application.
Example: express,body-parser,lodash,helmet,mysql all these are used while running the application use --save to put in dependencies while mocha,istanbul,chai,sonarqube-scanner all are used during development ,so put those in dev-dependencies .
npm link or npm install will also install the dev-dependency modules along with dependency modules in your project folder
Read Complete And Forget --save-dev Headache
Simplest answer is that --save-dev is useful when you are creating packages for other developers and want to host your package at NPM Registry like lodash, mongoose, express etc. When you are building or writing a Node Server there is no difference between --save and --save-dev because your Node Server implementation is private to you and you will never publish it on NPM.
How NPM Install Works
Whenever we install a new package using npm like npm install express then NPM installs that package to our system and put it into node_modules folder, now NPM will analyze the package.json file of newly installed package i.e express in this case, after analyzing NPM will install all those packages which were mentioned in dependencies section of package.json file of express package. After installing those packages on which express was dependent NPM again analyze the package.json file of all newly installed packages and again install the packages for them, this cycle goes on until all packages are available into node_modules folder to function properly. You can check package dependencies by running npm list in terminal where terminal should point location of your project directory.
How --save-dev Is Related To Above Explained Stuff
Suppose you want to create a new package like express, now while development of this new package you probably want to write some unit testing code and test the package with any other available testing package let's assume mocha in this case. Now you know mocha is only required to test the package not required to use the package. In this case you should install mocha using --save-dev flag, otherwise NPM will install it whenever a developer install your package using NPM. So if we want a dependency not installed when someone install our package from NPM we must install that package using --save-dev in development phase.
Last Thing
Do not mix --save-dev with collaboration development, if someone cloned your package code from a source version control system like github then NPM will surely install all devDependencies i.e package installed using --save-dev also.
Clear answers are already provided. But it's worth mentioning how devDependencies affects installing packages:
By default, npm install will install all modules listed as dependencies in package.json . With the --production flag (or when the NODE_ENV environment variable is set to production ), npm will not install modules listed in devDependencies .
See: https://docs.npmjs.com/cli/install
When you install an npm package using npm install <package-name>, you are installing it as a dependency.
The package is automatically listed in the package.json file, under the dependencies list (as of npm 5: before you had to manually specify --save).
ex. npm install lodash
After pressing enter check your package.json file.
"dependencies": {
"lodash": "4.x",
},
When you add the -D flag, or --save-dev, you are installing it as a development dependency, which adds it to the devDependencies list.
ex. npm install --save-dev lite-server
After pressing enter check your package.json file
"devDependencies": {
"lite-server": "^2.6.1"
},
Development dependencies are intended as development-only packages, that are unneeded in production. For example testing packages, webpack, or Babel.
When you go in production, if you type npm install and the folder contains a package.json file, they are installed, as npm assumes this is a development deploy.
You need to set the --production flag (npm install --production) to avoid installing those development dependencies.
All explanations here are great, but lacking a very important thing: How do you install production dependencies only? (without the development dependencies).
We separate dependencies from devDependencies by using --save or --save-dev.
To install all we use:
npm i
To install only production packages we should use:
npm i --only=production
You generally don't want to bloat production package with things that you only intend to use for Development purposes.
Use --save-dev (or -D) option to separate packages such as Unit Test frameworks (jest, jasmine, mocha, chai, etc.)
Any other packages that your app needs for Production, should be installed using --save (or -S).
npm install --save lodash //prod dependency
npm install -S moment // " "
npm install -S opentracing // " "
npm install -D jest //dev only dependency
npm install --save-dev typescript //dev only dependency
If you open the package.json file then you will see these entries listed under two different sections:
"dependencies": {
"lodash": "4.x",
"moment": "2.x",
"opentracing": "^0.14.1"
},
"devDependencies": {
"jest": "22.x",
"typescript": "^2.8.3"
},
--save-dev (only used in the development, not in production)
--save (production dependencies)
--global or -g (used globally i.e can be used anywhere in our local system)
People use npm on production to do wicked cool stuff, Node.js is an example of this, so you don't want all your dev tools being run.
If you are using gulp (or similar) to create build files to put on your server then it doesn't really matter.
Basically We Write
npm install package_name
But specially for Testing Purpose we don't need to run some package while Application is Running in Normal State so that Node introduce good way to solve this problem. Whenever we write
npm install package_name --save-dev
at that time this package is only installed for development purpose.
I want to add some of my ideas as
I think all differences will appear when someone uses your codes instead of using by yourself
For example, you write an HTTP library called node's request
In your library,
you used lodash to handle string and object, without lodash, your codes cannot run
If someone uses your HTTP library as a part of his code. Your codes will be compiled with his.
your codes need lodash, So you need to put in dependencies to compile
If you write a project like monaco-editor, which is a web editor,
you have bundled all your codes and your product env library using webpack, when build completed, only have a monaco-min.js
So someone doesn't care whether --save or --save-dependencies, only he needs is monaco-min.js
Summary:
If someone wants to compile your codes (use as a library),
put lodash which used by your codes into dependencies
If someone want to add more feature to your codes, he needs unit test and compiler, put these into dev-dependencies
as --save is default option for npm, so I use
npm i package
and for --save-dev, I use
npm i package -D
default option will install package as project dependency where as -D is for development dependencies like testing, lint etc. and install package for development process
you can find all the flags here https://docs.npmjs.com/cli/v8/commands/npm-install
I have an application which has the usual set of dependencies on third party modules (e.g. 'express') specified in the package.json file under dependencies. E.g.
"express" : "3.1.1"
I would like to structure my own code modularly and have a set of local (meaning on the file system I am currently in) modules be installed by the package.json. I know that I can install a local module by running:
npm install path/to/mymodule
However, I don't know how to make this happen via the package.json dependencies structure. Using the --save option in this command is simply putting "mymodule": "0.0.0" into my package.json (doesn't reference the filepath location). If i then remove the installed version from node_modules, and try to re-install from the package.json, it fails (because it looks for "mymodule" in the central registry, and doesn't look locally).
I'm sure the is a way of telling the "dependencies": {} structure that I want it to be installed from a file system path, but don't know how.
Anyone else had this problem?
Thanks.
npm install now supports this
npm install --save ../path/to/mymodule
For this to work mymodule must be configured as a module with its own package.json. See Creating NodeJS modules.
As of npm 2.0, local dependencies are supported natively. See danilopopeye's answer to a similar question. I've copied his response here as this question ranks very high in web search results.
This feature was implemented in the version 2.0.0 of npm. For example:
{
"name": "baz",
"dependencies": {
"bar": "file:../foo/bar"
}
}
Any of the following paths are also valid:
../foo/bar
~/foo/bar
./foo/bar
/foo/bar
syncing updates
Since npm install <folder> adds the package in the directory as a symlink in the current project any changes to the local package are automatically synced.
See: Local dependency in package.json
It looks like the answer is npm link: https://docs.npmjs.com/cli/link
I couldn't find a neat way in the end so I went for create a directory called local_modules and then added this bashscript to the package.json in scripts->preinstall
#!/bin/sh
for i in $(find ./local_modules -type d -maxdepth 1) ; do
packageJson="${i}/package.json"
if [ -f "${packageJson}" ]; then
echo "installing ${i}..."
npm install "${i}"
fi
done
After struggling much with the npm link command (suggested solution for developing local modules without publishing them to a registry or maintaining a separate copy in the node_modules folder), I built a small npm module to help with this issue.
The fix requires two easy steps.
First:
npm install lib-manager --save-dev
Second, add this to your package.json:
{
"name": "yourModuleName",
// ...
"scripts": {
"postinstall": "./node_modules/.bin/local-link"
}
}
More details at https://www.npmjs.com/package/lib-manager. Hope it helps someone.
You can just add to your package.json file in your project
"package-name" : "path/to/package"
and then run npm i in your project
At work we have a common library that is used by a few different projects all in a single repository. Originally we used the published (private) version (npm install --save rp-utils) but that lead to a lot of needless version updates as we developed. The library lives in a sister directory to the applications and we are able to use a relative path instead of a version. Instead of "rp-utils": "^1.3.34" in package.json it now is:
{
"dependencies": { ...
"rp-utils": "../rp-utils",
...
the rp-utils directory contains a publishable npm package
use install-local
I had issues with conflicting react installations from the local dependency.
I solved the error by using install-local npm package. This package does not create symlinks, which solved my issue.
Steps:
run npm i -g install-local
run npx install-local --save <local-path> inside the target repository to install the local dependency
Further reading: https://www.npmjs.com/package/install-local
The error I received, when trying to install the local package with npm install --save <local-directory>:
Error: Invalid hook call. Hooks can only be called inside of the body of a function component. This could happen for one of the following reasons:
You might have mismatching versions of React and the renderer (such as React DOM)
You might be breaking the Rules of Hooks
You might have more than one copy of React in the same app
If it's acceptible to simply publish your modules preinstalled in node_modules alongside your other files, you can do it like this:
// ./node_modules/foo/package.json
{
"name":"foo",
"version":"0.0.1",
"main":"index.js"
}
// ./package.json
...
"dependencies": {
"foo":"0.0.1",
"bar":"*"
}
// ./app.js
var foo = require('foo');
You may also want to store your module on git and tell your parent package.json to install the dependency from git: https://npmjs.org/doc/json.html#Git-URLs-as-Dependencies