Webpack config for Rails

application.js

//= require main.bundle

main.js

window.React = require('react/addons')
window.Router = require('react-router')

// ...

webpack.config.js

/**
 * @see http://webpack.github.io/docs/configuration.html for webpack configuration options
 */
module.exports = {
  // 'context' sets the directory where webpack looks for module files you list in your 'require' statements
  context: __dirname + '/app/assets/javascripts/webpack',

  // 'entry' specifies the entry point, where webpack starts reading all
  // dependencies listed and bundling them into the output file.
  entry: './main.js',

  // 'output' specifies the filepath for saving the bundled output generated by wepback.
  // It is an object with options, and you can interpolate the name of the entry
  // file using '[name]' in the filename.
  // You will want to add the bundled filename to your '.gitignore'.
  output: {
    filename: '[name].bundle.js',
    // We want to save the bundle in the same directory as the other JS.
    path: __dirname + '/app/assets/javascripts',
  },

  // Enable source map support
  devtool: "#eval-source-map",

  module: {
    loaders: [
      { test: /\.js$/, exclude: /node_modules/, loader: "6to5-loader"},
      { test: /\.coffee$/, loader: "coffee" }
    ]
  },

  resolve: {
    extensions: ["", ".coffee", ".js"]
  }
};