The npm install -s flag explained

When installing packages from npm, you may see the -s flag added to the npm install command as follows:

npm install -s

The -s flag is a shorthand for the silent configuration, which sets the log level of your npm installation process to nothing.

The following Terminal commands are all equal:

npm install -s
npm install --silent
npm install --loglevel silent

When you install npm packages using the -s flag, then npm won’t log any output to the console. You won’t be able to know whether the installation is successful or not from the Terminal.

A regular npm install command will show the following output:

$ npm install react

added 4 packages, and audited 17 packages in 2s

2 packages are looking for funding
  run `npm fund` for details

found 0 vulnerabilities
$

While npm install with the -s flag will show no output at all:

$ npm install vue -s
$

To know if your installation is successful, you need to open the package.json file and see if the package name is listed as dependencies.

Alternatively, you can open the node_modules/ folder and check if a folder with the package name exists there.

Keep in mind that the npm command flag is case-sensitive. The lower case -s flag is used to set the log level mode to silent, while the upper case -S flag is used to save installed packages to a package.json file as dependencies.

The npm save configuration has been set to true by default since npm version 5.