Javascript alert in php script
<p>I wanted to popup an alert box. After that, the site would redirect to main page. But, it seems that it directly redirect to the mainpage without alerting anything. </p>

<pre><code>if($registerquery)
    {
    ?&gt;

    &lt;script&gt;alert('received!')&lt;/script&gt;
&lt;?php
    }


    header("Location: mainpage.php");
    exit();


    ?&gt;
</code></pre>

<p>I wanted to do this to ensure users that the process of submission ended successfully. How can i alert something before the page redirect to mainpage and more importantly what causes this? I think the page should not have redirected before the alert box.(Before these codes, site registers what users submitted but not relevant i guess.)Thanks</p>
