wp_strip_all_tags is a built in WordPress function used to strip tags out of a given string. It is a modified, extended version of the PHP strip_tags function. strip_tags removes HTML and PHP tags from a string, and wp_strip_all_tags does two more things on top of that: it also removes the content of JavaScript and inline style tags, and it can optionally convert line breaks into white space.

The wp_strip_all_tags function is located in the /wp-includes/formatting.php file. Here is a simplified version of its definition –

function wp_strip_all_tags( $text, $remove_breaks = false ) {
    $text = preg_replace( '@<(script|style)[^>]*?>.*?</\\1>@si', '', $text );
    $text = strip_tags( $text );

    if ( $remove_breaks ) {
        $text = preg_replace( '/[\r\n\t ]+/', ' ', $text );
    }

    return trim( $text );
}

You can use this function in your php file for stripping HTML, PHP, JS, CSS tags.
Example:

$raw_text = '<div>Test paragraph.</div><script type="text/javascript">...</script><style type="text/css"></style><!-- Comment -->';
$striped_text = wp_strip_all_tags($raw_text, true);

// will return - "Test paragraph."

Arguments Reference:
– First parameter is the (string) you want to strip tags from.
– Second parameter is a (boolean), if set to true, line breaks will also be removed. The default is false, which keeps line breaks in place.