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.
# First way
echo -e 'USERNAME\nPASSWORD\nEMAIL' | npm login -e EMAIL -r REGISTRY
# Second way
npm login -e EMAIL -r REGISTRY << EOF