I found an npm package for this:
Install npm-cli-login and in the terminal/scripts use it as below:
npm-cli-login -u testUser -p testPass -e [email protected]
I found two other ways to pass the credentials without the need to use an external command, but be aware that these commands might not work in environments such as Jenkins.
Commands:
# First way
echo -e 'USERNAME\nPASSWORD\nEMAIL' | npm login -e EMAIL -r REGISTRY
# Second way
npm login -e EMAIL -r REGISTRY << EOF
USERNAME
PASSWORD
EMAIL
EOF