What causes Javascript to act differently on different machines?
<p>I just added a feature to a forum and while most users see and use it, a small number of people report strange behavior. I thought the problem might be due to browser caching and a ctrl+F5 solved it for some, but some can't fix it. (It's a simple editor button.)</p>

<p>I feel stupid even asking this but is there any way JS could not work on some machines the way it should?</p>

<p>EDIT: code added:</p>

<pre><code>    insertTab: function()
{
    if( this.get_selection() == "" )
    {
            var val = prompt( "How many lines of tablature?", '');
            if( val == '' ) return true;

            val = parseInt(val);

            var txt = "[code]\n";

            while ( val &gt; 0 )
            {
                txt += "------------------------------------------------------------------------------------------------" + "\n";
                txt += "------------------------------------------------------------------------------------------------" + "\n";
                txt += "------------------------------------------------------------------------------------------------" + "\n";
                txt += "------------------------------------------------------------------------------------------------" + "\n";
                txt += "------------------------------------------------------------------------------------------------" + "\n";
                txt += "------------------------------------------------------------------------------------------------" + "\n";
                txt += "\n";

                val--;
            }

            this.insert_text( txt + "[/code]" );
    }
    else
    {
        this.wrap_tags_lite( '[code]', '[/code]', 0);
    }
}
</code></pre>

<p>It works perfectly on every computer I've tried personally.</p>
