Quick and easy function to check if a plugin/theme/whatever has add/registered a shortcode in WordPress:
function is_shortcode_defined($shortcode) { global $shortcode_tags; if(isset($shortcode_tags[$shortcode])) return TRUE; else return FALSE; }
Just add this into your plugin or theme’s functions.php and wherever you need to check if the shortcode exists, just call is_shortcode_defined(“button”); or something similar from an if statement, as such:
if( ! is_shortcode_defined("button") ) { add_shortcode("button", "my_button_function"); }
Hope this helps.