// Old
var isverified = '<?php echo isset($_SESSION["verified"]); ?>';
if( isverified != "1" ) {
    //alert("Your session has timed out. Please log in again.");
    <?php
        wp_safe_redirect( 'welcome' );
    ?>
}

// New
var isverified = '<?php echo isset($_SESSION["verified"]); ?>';
if( isverified != "1" ) {
    //alert("Your session has timed out. Please log in again.");
    document.location.href = '<?php echo site_url('welcome') ?>';
}