Node cannot find module "fs" when using webpack

I'm using node.js and webpack to create a bundle. From what I've read, node.js should contain fs module for managing files. However when I call require("fs") I get an Cannot find module "fs" error. What should I do?

I came across this problem myself when bundling with webpack and found the answer on this thread.

The way to solve it for me was to use the following config:

module.exports = {
  entry: "./app",
  output: {
    path: __dirname,
    filename: "bundle.js"
  },
  module: {
      loaders: [
          {  
              test: /\.js$/,
              exclude: 'node_modules',
              loader: 'babel',
              query: {presets: ['es2015']},
          }
      ]
  },
  target: 'node'
};

By setting target to node webpack will make the necessary changes to bundle your node application

Edit: This answer targeted webpack 1.x which has now been superseded.