How to enable threaded comments in WordPress

To enable threaded comments in WordPress using functions.php, you can use the wp_list_comments_args filter in your theme’s functions.php file or in a separate plugin file. This filter is used to customize the arguments passed to the wp_list_comments function, which is used to display the comments list.

Here’s an example of how you can use the wp_list_comments_args filter to enable threaded comments in WordPress:

// Enable threaded comments in WordPress
// More snippets at wpunplugged.com 

function my_custom_comments_args( $args ) {
	// Enable threaded comments
	$args[ 'style' ] = 'ol';
	$args[ 'type' ] = 'all';
	$args[ 'callback' ] = 'my_custom_comments_callback';
	$args[ 'max_depth' ] = 3;

	return $args;
}
add_filter( 'wp_list_comments_args', 'my_custom_comments_args' );

function my_custom_comments_callback( $comment, $args, $depth ) {
	// Customize the display of the comments list
	...
}

This code will enable threaded comments by setting the style argument to ol (ordered list), the type argument to all (display all comments), and the callback argument to a custom function to customize the display of the comments list. The max_depth argument specifies the maximum depth of nested comments to display.

You can customize the display of the comments list by modifying the my_custom_comments_callback function. This function is called for each comment in the comments list, and it receives the comment object, the arguments array, and the depth of the comment as arguments.