如何像react-native一样在ReactJs中使用变量__DEV__？

Question

In my react-native projects I use the global variable __DEV__ and I would like to use something similar in my Typescript reactJs project but when I try to use it I get this error:

ReferenceError: __DEV__ is not defined 

How can I achieve this?

Answer 1

The global variable process has an attribute that allow to achieve this:

const isDev = process.env.NODE_ENV === 'development';