title: const keyword scope in Javascript
body: <pre><code>1. &gt;&gt;&gt; const a = 2
  2. &gt;&gt;&gt; var a = 3
  3. &gt;&gt;&gt; a = 4
  4. &gt;&gt;&gt; a // print 2
  </code></pre>
  
  <p>Why the operation line 3 is allowed? const seems more "global" than without any keyword...</p>