ContextReplacementPlugin refers to a require statement with an extension, such as the following:

require('./locale/' + name + '.json')

When you encounter an expression such as this, the plugin will infer the directory of ./local/ and a regular expression. If a name is not included at the time of compilation, then every file will be included as a module in the bundle. This plugin will allow the inferred information to be overridden.

The next plugin to discuss is HtmlWebpackPlugin.