NPM: Manage Dev and Prod Dependencies

When using $ npm install --dev the dependency is added into “devDependencies” inside the file packages.json.

When $ npm install is used it will install both devDependencies and dependencies by default. If the variable NODE_ENV is set to production it will install only dependencies.

To install only the production dependencies (dependencies) regardless of the value of the NODE_ENV variable, the flag --only should be used: $ npm install --only=production.