You could use a JavaScript alert to do what you’re asking, but the only way I can think of doing it would likely be a fair chunk of unnecessary added complexity.
I’ve written a small PHP script using the code from your example. If you have any difficulty amending it for your purposes, please don’t hesitate to let me know.
<?php
// die if not uninstalling
if( !defined( 'WP_UNINSTALL_PLUGIN' ) )
exit ();
// if the "act" variable hasn't been set, display a form
if (!isset($_GET["act"])) {
?>
<p>Would you like to keep the options configured by this plugin?</p>
<form action="<?php echo $_SERVER["REQUEST_URI"]; ?>">
<select name="act">
<option>Select choice..</option>
<option value="keep">Keep options</option>
<option value="delete">Delete options</option>
</select>
<input type="submit" value="Go" />
</form>
<?php
} else {
// if the "act" variable has been set, see if the user wants to delete the options..
if ($_GET["act"] == "delete") {
delete_option( 'my_options' );
echo "Options deleted; uninstallation successful.";
return;
} else {
// .. or keep them
echo "Options kept; uninstallation successful.";
return;
}
}
?>
** EDIT: PREFERENCE ROUTE **
OK, according to this post, apparently you shouldn’t / can’t use much more PHP in uninstall.php than the basic deleting of options etc.
As such, my advice would be this: create an option in your plugin settings which says “keep settings on deletion” or similar (called “DELETE_OPTIONS” in my example). Then use the following code in your uninstall.php:
<?php
$options = get_option('MY_PLUGIN_OPTIONS');
if ( true === $options['DELETE_OPTIONS'] ) {
delete_option('MY_PLUGIN_OPTIONS');
}
?>
Regards,
Duncan