How can you retrieve command line variables within your code by utilizing npm script in webpack?

Question

How can you retrieve command line variables within your code by utilizing npm script in webpack?

I'm trying to access command line parameters from an npm script in my "constants.js" file.

While I have been able to access parameters in the webpack.config.js file using process.env, it seems to be undefined in my app source files.

The scenario consists of running a script from the console like so:

npm webpack-dev-server --hot MY_PARAMETER=some_value

Afterwards, I want to somehow access MY_PARAMETER in my constants.js file by checking:

process.env.MY_PARAMETER === "some_value"   // true

If anyone could provide some assistance on this matter, I would greatly appreciate it. Thank you!

javascript npm webpack

Answer 1

Answer №1

If you come across a .env file, it is highly recommended to utilize dotenv-webpack (and optionally, string-replace-webpack-plugin or a similar tool). After reviewing the documentation, it is advised to include a .env.local entry in your VCS ignore file (.gitignore, .hgignore, etc.) for security reasons, and initialize the new DotenvPlugin with an object specifying the path, as shown below:

const DotEnvPlugin = require('dotenv-webpack');
module.exports = {
/* other settings */
  plugins: [
    // other plugins,
    new DotEnvPlugin({
      path:'.env.local',
      // safe: true, // load '.env.example' to verify the '.env' variables are all set. Can also be a string to a different file.
    })
  ]
}

In case you do not possess a .env file, consider utilizing the aforementioned string-replace-webpack-plugin and simply add those variables to your environment. You may need to seek guidance from your OS/administrator on how to proceed.

Lastly, remember that you can define these variables in a command-line call; just ensure they are placed before any executed command, like so (for bash shell):

MY_PARAMETER=some_value node_modules/.bin/webpack-dev-server --hot

Answer 2

If you come across a .env file, it is highly recommended to utilize dotenv-webpack (and optionally, string-replace-webpack-plugin or a similar tool). After reviewing the documentation, it is advised to include a .env.local entry in your VCS ignore file (.gitignore, .hgignore, etc.) for security reasons, and initialize the new DotenvPlugin with an object specifying the path, as shown below:

const DotEnvPlugin = require('dotenv-webpack');
module.exports = {
/* other settings */
  plugins: [
    // other plugins,
    new DotEnvPlugin({
      path:'.env.local',
      // safe: true, // load '.env.example' to verify the '.env' variables are all set. Can also be a string to a different file.
    })
  ]
}

In case you do not possess a .env file, consider utilizing the aforementioned string-replace-webpack-plugin and simply add those variables to your environment. You may need to seek guidance from your OS/administrator on how to proceed.

Lastly, remember that you can define these variables in a command-line call; just ensure they are placed before any executed command, like so (for bash shell):

MY_PARAMETER=some_value node_modules/.bin/webpack-dev-server --hot

How can you retrieve command line variables within your code by utilizing npm script in webpack?

Answer №1

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