JavaScript String concatenation bug on Firefox 3.6
<p>This is my simple script: </p>

<pre><code>&lt;script&gt;
    $("#adv").ready(function(){
        var x = 0;
    setInterval(function(){
            $("#adv").html('');
            x++;
            $('&lt;img src="http://url/adv'+x+'.png?u=1&amp;s=1&amp;a='+x+'" /&gt;').appendTo('#adv');
            if(x == 2) {
                x = 0;
            }
        }, 20000);

    });
  &lt;/script&gt;
</code></pre>

<p>Rotate image file every 20 seconds. Works perfectly but sometimes in server logs is see: </p>

<pre><code>GET /adv%2527+x+%2527.png   403 Mozilla/5.0%20(Macintosh;%20U;%20PPC%20Mac%20OS%20X%2010.4;%20en-US;%20rv:1.9.2.4)%20Gecko/20100611%20 *Firefox/3.6.4*

GET /adv%2527+x+%2527.png   403 Mozilla/5.0%20(Windows;%20U;%20Windows%20NT%206.1;%20pl;%20rv:1.9.2.23)%20Gecko/20110920%20Firefox/3.6.23 
</code></pre>

<p>So script concatenate script with quotas: <strong>/adv%2527+x+%2527.png</strong>
And this is only for Firefox 3.6.x</p>

<p>I also tested this on my Firefox 3.6 latest version, but this never happend for me.</p>

<p>anyone has idea how i should concatenate string to avoid this problem ? </p>
