npm-scriptsについて ref: http://qiita.com/axross/items/a2a0d148e40b66074858

file0.json

{
  "name": "myapp"
  "scripts": {
    "start":      "node app.js",
    "production": "NODE_ENV=production node app.js"
  }
}

file0.txt

{
  "name": "myapp"
  "scripts": {
    "start":      "node app.js",
    "production": "NODE_ENV=production node app.js"
  }
}

file1.sh

npm run-sctipt production

file1.txt

npm run-sctipt production

file2.json

{
  "name": "myapp"
  "scripts": {
    "start": "node app.js"
  },
  "config": {
    "port": "8080"
  }
}

file2.txt

npm run production

file3.js

http.createServer(function() {
  ;
}).listen(process.env.npm_package_config_port);

file3.txt

{
  "name": "myapp"
  "scripts": {
    "start": "node app.js"
  },
  "config": {
    "port": "8080"
  }
}

file4.sh

npm config set myapp:port 80

file4.txt

http.createServer(function() {
  ;
}).listen(process.env.npm_package_config_port);

file5.txt

npm config set myapp:port 80