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How to Set Run Time Env Variable In Webpack?

6 minutes read

To set a runtime environment variable in webpack, you can use the webpack DefinePlugin. This plugin allows you to create global constants which can be configured at compile time. You can define these variables in your webpack configuration file using the plugins property.


For example, to set a runtime environment variable called API_URL to "https://api.example.com", you can define it like this:

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const webpack = require('webpack');

module.exports = {
  // other webpack configuration settings
  plugins: [
    new webpack.DefinePlugin({
      'process.env': {
        API_URL: JSON.stringify('https://api.example.com')
      }
    })
  ]
};


With this configuration, you can access the API_URL variable in your code like this:

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console.log(process.env.API_URL); // Output: "https://api.example.com"


By setting runtime environment variables in webpack, you can have different configurations for development, staging, and production environments without changing the code.


How to set PORT environment variable in webpack?

To set the PORT environment variable in webpack, you can use the webpack.DefinePlugin to define the variable value.


Here's an example of how you can set the PORT environment variable in your webpack configuration:

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const webpack = require('webpack');

module.exports = {
  // other webpack configuration options

  plugins: [
    new webpack.DefinePlugin({
      'process.env.PORT': JSON.stringify(process.env.PORT || '8080')
    })
  ]
};


In this example, we are using the DefinePlugin to define the process.env.PORT variable with a default value of '8080'. If the PORT environment variable is already set, it will use that value instead.


You can then access the process.env.PORT variable in your code like so:

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const port = process.env.PORT;
console.log(`Server running on port ${port}`);


Make sure to restart webpack after making changes to the configuration file in order for the changes to take effect.


How to pass environment variables to webpack config?

To pass environment variables to webpack config, you can use the DefinePlugin provided by webpack. Here's how you can do it:

  1. Install webpack and webpack-merge if you haven't already:
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npm install webpack webpack-merge --save-dev


  1. In your webpack config file, require webpack and webpack-merge:
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const webpack = require('webpack');
const { merge } = require('webpack-merge');


  1. Define your environment variables in the config file:
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const envVariables = {
  API_URL: JSON.stringify(process.env.API_URL),
  DEBUG: process.env.DEBUG === 'true' // You can also convert the string value to boolean or number
};


  1. Merge the environment variables with the webpack config:
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const config = {
  // Your webpack configuration here
  plugins: [
    new webpack.DefinePlugin(envVariables)
  ]
};

module.exports = config;


  1. When running webpack, you can pass environment variables from the command line like this:
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API_URL=https://example.com DEBUG=true webpack


This way, the defined environment variables will be available in your webpack config and can be used in your project.


What are the benefits of using dotenv with webpack for setting env variables?

  1. Increased security: By using dotenv, you can securely store sensitive environment variables (such as API keys and passwords) in a separate .env file instead of hardcoding them into your webpack configuration files.
  2. Simplified configuration: Using dotenv with webpack makes it easier to manage different environment variables for development, testing, and production environments. You can customize the variables in the .env file based on the environment you are working in.
  3. Better scalability: As your project grows in complexity, managing environment variables manually can become cumbersome. Using dotenv with webpack allows you to seamlessly add, remove, and update environment variables without affecting your webpack configuration.
  4. Improved portability: By using dotenv with webpack, you can easily share your project with others without exposing sensitive information. The .env file can be kept out of version control, making it more secure and portable across different environments.
  5. Enhanced flexibility: With dotenv, you can easily switch between different environments and configurations without having to modify your webpack settings. This flexibility allows you to streamline your development workflow and focus on writing code instead of managing environment variables.


What impact does setting env variable have on webpack bundle size?

Setting environment variables in webpack can have an impact on the bundle size depending on how these variables are being used in the code.


If the environment variables are used to conditionally include or exclude certain code blocks, modules, or dependencies, then the size of the bundle can change based on how these conditionals are evaluated. For example, if an environment variable is used to determine which features or functionalities are included in the bundle, setting it to different values can result in a larger or smaller bundle size.


Additionally, if environment variables are used to configure webpack plugins or loaders, they can also affect the output bundle size. For example, certain configurations or optimizations may be applied based on the value of an environment variable, which can impact the final size of the bundle.


Overall, the impact of setting environment variables on webpack bundle size will depend on how they are used in the code and configurations, and it is important to consider these factors when setting environment variables to optimize the size of the bundle.


How to configure webpack to use environment variables?

To configure webpack to use environment variables, you can use the webpack.EnvironmentPlugin to expose your variables to your code as global variables. Here's how you can configure webpack to use environment variables:

  1. Install the webpack.EnvironmentPlugin:
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npm install webpack webpack-cli webpack-dev-server webpack.EnvironmentPlugin --save-dev


  1. Update your webpack configuration file (usually webpack.config.js) to use the EnvironmentPlugin:
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const webpack = require('webpack');

module.exports = {
  // your webpack config options

  plugins: [
    new webpack.EnvironmentPlugin({
      NODE_ENV: 'development',
      API_URL: 'http://localhost:3000'
    })
  ]
};


In the above configuration, we are exposing two environment variables, NODE_ENV and API_URL. These variables can now be accessed in your code using process.env.NODE_ENV and process.env.API_URL.

  1. Rebuild your webpack bundle to incorporate the changes:
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webpack --mode production


Now your webpack bundle will use the environment variables defined in your webpack configuration file. You can also define your environment variables as actual environment variables in your system or in a .env file for better security and flexibility.


How to access process.env variables in webpack dev server?

To access process.env variables in webpack dev server, you can define these variables in a .env file (e.g., .env.development) at the root of your project. Then, you can use a package like dotenv to load these variables into process.env. Here is a step-by-step guide on how to access process.env variables in webpack dev server:

  1. Create a .env.development file at the root of your project and define your environment variables like this:
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MY_VARIABLE=value


  1. Install the dotenv package by running the following command in your terminal:
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npm install dotenv --save-dev


  1. In your webpack configuration file (e.g., webpack.config.js), add the following code at the top to load the .env file:
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require('dotenv').config({
  path: '.env.development'
});


  1. Now, you can access the MY_VARIABLE variable in your webpack configuration file like this:
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module.exports = {
  plugins: [
    new webpack.DefinePlugin({
      'process.env.MY_VARIABLE': JSON.stringify(process.env.MY_VARIABLE)
    })
  ]
}


  1. Restart your webpack dev server, and you should be able to access process.env.MY_VARIABLE in your code.


By following these steps, you can access process.env variables in webpack dev server by defining them in a .env file and loading them into process.env using the dotenv package.

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