Why I can delete property of global object in javascript?
<p>I'am novice in JS. While reading the book, I found that some examples do not work in firebug or maybe I simply don't understand something.</p>

<p>For example:</p>

<pre><code>&gt;&gt;&gt; var a = 1;
undefined
&gt;&gt;&gt; a
1
&gt;&gt;&gt; this.a
1
&gt;&gt;&gt; delete a
true
&gt;&gt;&gt; a;
ReferenceError: a is not defined
</code></pre>

<p>Why I can delete property of a global object? I read that such variables are nonconfigurable and cannot be deleted.</p>

<p>Maybe that is not important, but it will be better if i understand what is going on:)</p>
