I need help understanding a simple JavaScript script
<pre><code>if(document.frmMain.POL_NO.value == "")
{
    alert("Select Policy Number");
    document.frmMain.ENDT_NO.value="";
    document.frmMain.POL_NO.focus();
    return false;     
}
</code></pre>

<p>Can anyone explain the above code to me? I am new to Javascript.</p>
