Nincompoops Producing Methane

    TypeScript icon, indicating that this package has built-in type declarations

    2.1.0 • Public • Published


    react-inject-env is a tool that allows you to inject your environment variables after building the static files, allowing you to deploy the same build to multiple environments quickly.


    Sample project

    1. Install react-inject-env

    npm install react-inject-env --save-dev
    yarn add react-inject-env --dev

    2. Update Code

    • Add the following to index.html
    <script src='/env.js'></script>
    • Create a new file called env.js and copy the following code:
    export const env = { ...process.env, ...window['env'] }
    • Replace all instances of process.env with the newly created env variable
    import { env } from './env'
    export const App = () => {
      return (
        <div style={{backgroundColor: env.REACT_APP_COLOR}}>

    3. Build your static files

    If you are using create-react-app, the command should be npm run build or react-scripts build.

    4. Inject environment variables

    [env variables] npx react-inject-env set

    Pass in all your environment variables.

    # with a black background
    REACT_APP_COLOR=black REACT_APP_MAIN_TEXT="Black Background" npx react-inject-env set
    # with a blue background
    REACT_APP_COLOR=blue REACT_APP_MAIN_TEXT="Blue Background" npx react-inject-env set
    # for windows
    set REACT_APP_COLOR=navy&& set REACT_APP_MAIN_TEXT=Navy Background&& npx react-inject-env set

    Additional options

    -d / --dir: The location of your static build folder. Defaults to ./build

    -n / --name: The name of the env file that is outputted. Defaults to env.js

    -v / --var: The variable name in window object that stores the environment variables. The default is env (window.env). However if you already have a variable called window.env, you may rename it to avoid conflicts.

    .env / dotenv

    .env files are supported. react-inject-env will automatically detect environment variables in your .env file located in your root folder.

    Note: Environment variables passed in through the command line will take precedence over .env variables.


    In step #2, create a file called env.ts instead of env.js

    declare global {
      interface Window {
        env: any
    // change with your own variables
    type EnvType = {
      REACT_APP_COLOR: string,
      REACT_APP_MAIN_TEXT: string,
      REACT_APP_LINK_URL: string,
      REACT_APP_LOGO_URL: string
    export const env: EnvType = { ...process.env, ...window.env }

    Docker / CICD

    npx-react-env works well with both Docker and CI/CD.

    Sample usage with Docker

    FROM node:16.10-slim
    COPY . /app
    WORKDIR /app
    RUN npm install
    RUN npm run build
    EXPOSE 8080
    ENTRYPOINT npx react-inject-env set && npx http-server build
    docker build . -t react-inject-env-sample-v2
    docker run -p 8080:8080 \                   
    -e REACT_APP_COLOR=yellow \
    -e REACT_APP_LOGO_URL=./logo512.png \
    -e REACT_APP_MAIN_TEXT="docker text" \

    Previous Version v1.0

    For instructions on the previous version, you may follow the v1.0 guide here.


    Why do I need this?

    A typical CI/CD process usually involves building a base image, followed by injecting variables and deploying it.

    Unfortunately React applications does not allow for this workflow as it requires environment variables to be present before building it.

    There have been a few workarounds, with the most common solution being to load environment variables from an external source. However this now causes the additional problem that environment variables can only be accessed asynchronously.


    react-inject-env attempts to solve this problem in the simplest, and most straightforward way with the following goals in mind:

    1. Does not require a rebuild
    2. Minimal code change required
    3. Allows synchronous access of environment variables
    4. Supports a wide amount of tools and scripts
    5. Works with command line environment variables
    6. Simple and straightforward


    react-inject-env was built with support for both create-react-app and dotenv.

    However due to the simplicity of it, it should work with almost all scripts and tools.




    npm i react-inject-env

    DownloadsWeekly Downloads






    Unpacked Size

    26.2 kB

    Total Files


    Last publish


    • codegowhere
    • es-lynn