Passing environment-dependent variables in webpack

I’m trying to convert an angular app from gulp to webpack. in gulp I use gulp-preprocess to replace some variables in the html page (e.g. database name) depending on the NODE_ENV. What is the best way of achieving a similar result with webpack?

Answer

There are two basic ways to achieve this.

DefinePlugin

new webpack.DefinePlugin({
    'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV || 'development')
}),

Note that this will just replace the matches “as is”. That’s why the string is in the format it is. You could have a more complex structure, such as an object there but you get the idea.

EnvironmentPlugin

new webpack.EnvironmentPlugin(['NODE_ENV'])

EnvironmentPlugin uses DefinePlugin internally and maps the environment values to code through it. Terser syntax.

Alias

Alternatively you could consume configuration through an aliased module. From consumer side it would look like this:

var config = require('config');

Configuration itself could look like this:

resolve: {
    alias: {
        config: path.join(__dirname, 'config', process.env.NODE_ENV)
    }
}

Let’s say process.env.NODE_ENV is development. It would map into ./config/development.js then. The module it maps to can export configuration like this:

module.exports = {
    testing: 'something',
    ...
};