Javascript global variables
<p>is there any difference between declaring a variable</p>

<pre><code>var a=0;//1
</code></pre>

<p>and this way</p>

<pre><code>a=0;//2
</code></pre>

<p>or</p>

<pre><code>window.a=0;//3
</code></pre>

<p>in global scope?</p>
