title: Constant declaration with block
body: <p>Recently I was looking into Firefox <a href="https://addons.mozilla.org/en-US/developers/builder" rel="noreferrer">Add-on Builder</a> SDK sources, and stumbled on such constants declaration:</p>
  
  <pre><code>const { getCodeForKey, toJSON } = require("../../keyboard/utils");
  </code></pre>
  
  <p>I could find information about <a href="http://www.commonjs.org/specs/modules/1.0/" rel="noreferrer">CommonJS Modules</a>, but left part of this assignment slightly confuses me, since it must be language specific, and I couldn't google anything on that.</p>
  
  <p>Can someone point me to some specification/draft that explains what's going on here?</p>