using variable inside .env file for create react app

Question

using variable inside .env file. In create react app.

I am trying to re use the env variable in other env variables, is this correct of way of doing, but i am not getting the value .

.env

A=hello
B=${A}/new

Could you try with require('dotenv').config() if you didn't ? — Ahmet Zeybek
– Ahmet Zeybek, Commented Jan 30, 2020 at 11:04
so i need to install dotenv package additionally and use it isn't — Beginner
– Beginner, Commented Jan 30, 2020 at 11:06
this is indeed a fun question... I honestly don't know if it is even possible, I've never seen this before. However, it's only a env file. Whenever you need to change some env variable, you'll need to change this file, so why don't just put B=hello/new ? — Diogo Lessa
– Diogo Lessa, Commented Jan 30, 2020 at 11:21
@DiogoLessa trying the impossible things is everyday's developer job thats how the requirement comes hahha :) and thats how people think of javascript — Beginner
– Beginner, Commented Jan 30, 2020 at 11:30

evolon · Accepted Answer · 2020-01-30 11:36:44Z

2

It's important to realize that env variables are only available in node environment and not in the browser.

But if you're using create-react-app, It does some tricks for you and simulates the same behavior inside the browser, only if you put the REACT_APP_ prefix before your env variables.

As the create-react-app docs says here:

Note: You must create custom environment variables beginning with REACT_APP_. Any other variables except NODE_ENV will be ignored to avoid accidentally exposing a private key on the machine that could have the same name. Changing any environment variables will require you to restart the development server if it is running.

edited Jan 30, 2020 at 11:36

answered Jan 30, 2020 at 11:33

evolon

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3 Comments

Beginner Over a year ago

that i know but if i add the prefix with REACT_APP will it work ?

fayeed Over a year ago

@DILEEPTHOMAS check this doc

evolon Over a year ago

Yes. @DILEEPTHOMAS, when create-react-app includes your env files in your final bundle, it ignores the ones that don't have REACT_APP_ prefix.

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