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There is no difference between development and production in Node.js, i.e., there are no specific settings you need to apply to make Node.js work in a production configuration. However, a few libraries in the npm registry recognize using the NODE_ENV variable and default it to a development setting. Always run your Node.js with the NODE_ENV=production set.

A popular way of configuring your application is by using the twelve factor methodology.

An environment is a digital platform or a system where engineers can build, test, deploy, and manage software products. Conventionally, there are four stages or types of environments where our application is run:

  • Development
  • Testing
  • Staging
  • Production

The fundamental problem of NODE_ENV stems from developers combining optimizations and software behavior with the environment their software is running on. The result is code like the following:

if (process.env.NODE_ENV === 'development') {
  // ...
}

if (process.env.NODE_ENV === 'production') {
  // ...
}

if (['production', 'staging'].includes(process.env.NODE_ENV)) {
  // ...
}

While this might look harmless, it makes the production and staging environments different, thus making reliable testing impossible. For example a test and thus a functionality of your product could pass when NODE_ENV is set to development but fail when setting NODE_ENV to production. Therefore, setting NODE_ENV to anything but production is considered an antipattern.