="token comment">// Uncaught SyntaxError: Identifier 'firstName' has already been declared</span>
<span aria-hidden="true" class="line-numbers-rows"><a href="#C6_L1" id=C6_L1></a><a href="#C6_L2" id=C6_L2></a><a href="#C6_L3" id=C6_L3></a></span></code></pre>
<p>Note that <code>const</code> does not mean that the value it refers to cannot change.
If you have an array or an object, you can change their properties:</p>
<pre class="language-javascript line-numbers"><code class="javascript language-javascript">