Checking size of importing all of React Router

app.js

import React from 'react'
import {render} from 'react-dom'

import 'react-router'

let App = React.createClass({
  render() {
    return <div>
      <h1>Hello world!</h1>
    </div>
  }
})

render(<App/>, document.querySelector('#app'))

package.json

{
  "scripts": {
    "test": "react build app.js && source-map-explorer dist/app.js"
  },
  "dependencies": {
    "react": "^15.1.0",
    "react-dom": "^15.1.0",
    "react-router": "^2.4.1"
  },
  "devDependencies": {
    "nwb": "0.11.x",
    "source-map-explorer": "^1.3.2"
  }
}