The mergeConfig method will intelligently merge your new config with the existing Webpack config (thanks to webpack-merge).
There are a few additional config options on the Elixir object.
elixir.isProduction
By default checks for the production flag from the terminal (-p)
elixir.rootPath
The root of the project
elixir.config
A configured instance of ElixirConfig
elixir.versioning
Defaults to elixir.isProduction
elixir.base64SourceSize
Defaults to 0. When configured as a number of bytes, any assets referenced in the CSS files you compile will be inlined as Base64 objects in your compiled output. ( e.g. 1000000 = 1000kb )