NormalModuleReplacementPlugin

The NormalModuleReplacementPlugin allows you to replace resources that match resourceRegExp with newResource. If newResource is relative, it is resolved relative to the previous resource. If newResource is a function, it is expected to overwrite the request attribute of the supplied resource.

This can be useful for allowing different behaviour between builds.

new webpack.NormalModuleReplacementPlugin(
  resourceRegExp,
  newResource
);

Basic Example

Replace a specific module when building for a development environment.

Say you have a config file some/path/config.development.module.js and a special version for production in some/path/config.production.module.js

Just add the following plugin when building for production:

new webpack.NormalModuleReplacementPlugin(
  /some\/path\/config\.development\.js/,
  './config.production.js'
);

Advanced Example

Conditional build depending on an specified environment.

Say you want a configuration with specific values for different build targets.

module.exports = function(env) {
  var appTarget = env.APP_TARGET || 'VERSION_A';
  return {
    plugins: [
      new webpack.NormalModuleReplacementPlugin(/(.*)-APP_TARGET(\.*)/, function(resource) {
        resource.request = resource.request.replace(/-APP_TARGET/, `-${appTarget}`);
      })
    ]
  };

};

Create the two config files:

app/config-VERSION_A.js

export default {
  title : 'I am version A'
};

app/config-VERSION_B.js

export default {
  title : 'I am version B'
};

Then import that config using the keyword you're looking for in the regexp:

import config from 'app/config-APP_TARGET';
console.log(config.title);

And now you just get the right config imported depending on which target you're building for:

webpack --env.APP_TARGET VERSION_A
=> 'I am version A'

webpack --env.APP_TARGET VERSION_B
=> 'I am version B'