What does -save-dev mean in npm install grunt --save-dev

Question

I ve just started using Grunt js  It is pretty hard to set up and I am at the point of creating a package json file   Following this tutorial  it says there are 3 ways to create a package json file   The first is to do npm install grunt --save-dev  But what does --save-dev means  I tried looking but it ends in vain

User · Accepted Answer

--save-dev  Package will appear in your devDependencies    According to the npm install 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    In other words  when you run npm install  your project s devDependencies will be installed  but the devDependencies for any packages that your app depends on will not be installed  further  other apps having your app as a dependency need not install your devDependencies  Such modules should only be needed when developing the app  eg grunt  mocha etc    According to the package json docs  Edit  Attempt at visualising what npm install does    yourproject   dependency installed   dependency installed   dependency installed devDependency NOT installed  devDependency NOT installed  devDependency installed   dependency installed devDependency NOT installed

User · Answer

To add on to Andreas  answer  you can install only the dependencies by using   npm install --production

User · Answer

When you use the parameter  --save  your dependency will go inside the  1 below in package json  When you use the parameter  --save-dev  your dependency will go inside the  2 below in package json     1   dependencies   these packages are required by your application in production    2   devDependencies   these packages are only needed for development and testing

User · Answer

There are  at least  two types of package dependencies you can indicate in your package json files    Those packages that are required in order to use your module are listed under the  dependencies  property  Using npm you can add those dependencies to your package json file this way   npm install --save packageName  Those packages required in order to help develop your module are listed under the  devDependencies  property  These packages are not necessary for others to use the module  but if they want to help develop the module  these packages will be needed  Using npm you can add those devDependencies to your package json file this way   npm install --save-dev packageName

User · Answer

For me the first answer appears a bit confusing  so to make it short and clean   npm install  lt package name gt  saves any specified packages into dependencies by default  Additionally  you can control where and how they get saved with some additional flags   npm install  lt package name gt  --no-save Prevents saving to dependencies   npm install  lt package name gt  ---save-dev updates the devDependencies in your package   These are only used for local testing and development   You can read more at in the dcu

User · Answer

--save-dev means  quot needed only when developing quot   e g  the final users using your package will not want need care about what testing suite you used  they will only want packages that are absolutely required to run your code in a production environment  This flag marks what is needed when developing vs production

User · Answer

Documentation from npm for npm install  lt package-name gt  --save and npm install  lt package-name gt  --save-dev can be found here   https   docs npmjs com getting-started using-a-package json the-save-and-save-dev-install-flags  A package json file declares metadata about the module you are developing  Both aforementioned commands modify this package json file  --save will declare the installed package  in this case  grunt  as a dependency for your module  --save-dev will declare it as a dependency for development of your module   Ask yourself  will the installed package be required for use of my module  or will it only be required for developing it

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