When installing a package using npm (the package manager for Node.js), you can use the --save
flag to add the package to your project’s dependencies
in the package.json
file. This indicates that the package is required for your project to run and should be installed when running npm install
.
On the other hand, the --save-dev
flag adds the package to your project’s devDependencies
in the package.json
file. This indicates that the package is only needed for development, such as for testing or building, and should not be included in the production environment.
For example, if you are installing a testing library like Mocha, you would use the --save-dev
flag, because you don’t need the testing library to run the production version of your app. On the other hand, if you are installing a library like Express, which is required for your app to run, you would use the --save
flag.
Here’s an example of installing a package with the --save
flag:
npm install express --save
And here’s an example of installing a package with the --save-dev
flag:
npm install mocha --save-dev