Guidelines for treating NODE_ENV in new code

[valango]

A question of to what value should process.env.NODE_ENV default to if not set, is a quite important one. There is plenty of discussion about it out there, ones advocating 'production' and others 'development'. This can be confusing.

I suggest publishing the following suggestion somewhere in guides chapter.

If process.env.NODE_ENV is undefined, the code should assume default value as follows:

• generic library code: 'development' as the best choice when writing new code;
• (server) application code: 'development' because in real life this code is launced by script or loader, explicitly setting the NODE_ENV value;
• utility package code: 'production', because it's likely a developer wants to debug his/her own code, not the code of installed npm packages or tools like npm or rimraf.