how to find or decrypt the url of javascript:void(0)
<p>well, I just downloaded a code from internet and it has </p>

<pre><code>&lt;a href="javascript:void(0)" class="action"&gt;login&lt;/a&gt;
</code></pre>

<p>when i click on it, it shows a pop up.
I want to use that pop on any other button , but does no know how to do that. can any one please explain me how it can be done or how the current given line is working.
I am just new to this, so please dont be mad if it is a stupid question.
Thank you</p>