npm i -g writeconf

writeconf --port 8888 --apiHost http://myapi.com

This will result in a config.json file:

{
  port: 8888,
  apiHost: 'http://myapi.com'
}

When running the command again with changed arguments, it will extend the existing config.json file

writeconf --port 666

output:

{
  port: 666,
  apiHost: 'http://myapi.com'
}