Adding the condition that it appends only once
<p>Here's my jQuery snippet </p>

<pre><code>$(document).ready(function() {

$("#button").click(function(e) {
    $("body").append('Source:CIA World Factbook');
});


}); 
</code></pre>

<p>I want to append only once by clicking on a button,</p>

<p>Here's the source for the button,</p>

<pre><code>&lt;div id="button"&gt; Show Sources &lt;/div&gt;
</code></pre>

<p>How can I achieve it?</p>
