What do the --save flags do with npm install

Question

I see instructions to install a package with either

npm install 

or

npm install  --save         


        

Answer 1

npm install takes 3 exclusive, optional flags which save or update the package version in your main package.json:

-S, --save: Package will appear in your dependencies.

-D, --save-dev: Package will appear in your devDependencies.

-O, --save-optional: Package will appear in your optionalDependencies.

When using any of the above options to save dependencies to your package.json, there is an additional, optional flag:

-E, --save-exact: Saved dependencies will be configured with an exact version rather than using npm's default semver range operator. Further, if you have an npm-shrinkwrap.json then it will be updated as well.

is optional. The package will be downloaded from the registry associated with the specified scope. If no registry is associated with the given scope the default registry is assumed. See npm-scope.

Note: if you do not include the @-symbol on your scope name, npm will interpret this as a GitHub repository instead, see below. Scopes names must also be followed by a slash.

Examples:

npm install sax --save
npm install githubname/reponame
npm install @myorg/privatepackage
npm install node-tap --save-dev
npm install dtrace-provider --save-optional
npm install readable-stream --save --save-exact

Note: If there is a file or folder named in the current working directory, then it will try to install that, and only try to fetch the package by name if it is not valid.

(from official docs) https://docs.npmjs.com/cli/install