title: eslint: error Parsing error: The keyword 'const' is reserved
body: <p>I am getting this error from ESLint:</p>
  
  <pre class="lang-none prettyprint-override"><code>error  Parsing error: The keyword 'const' is reserved
  </code></pre>
  
  <p>from this code:</p>
  
  <pre><code>const express = require('express');
  const app = express();
  const _ = require('underscore');
  </code></pre>
  
  <p>I've tried removing <code>node_modules</code> and reinstalling all npm packages (as suggested <a href="https://stackoverflow.com/questions/38757885/setting-up-airbnb-eslint-with-react-and-webpack">here</a>), but to no avail.</p>