How to start node app with development flag?

Question

At top of my app.js file I put

NODE_ENV=\'development\';

but I get error that NODE_ENV is not defined. But in the nodejs documentation is says

Answer 1

It is better to start your app in dev mode like this:

NODE_ENV=development node app.js

But if you really wanted to set it your app file just set it like this:

process.env.NODE_ENV= "development"