error prone jquery extending

Question

Anybody familiar with patterns for:

• Checking for existing jQuery extension most safely?
• And how to exit from it safely if code can not be executed.

Like

(function($){
    if (jQuery.fn.pluginName)
    ......
    }
})(jQuery);

10x, BR

Answer 1

The $.fn namespace is populated with functions. If the plugin exists you can use this

if ($.fn.myPlugin instanceof Function) {
    // the plugin exists
} else {
    // the plugin does not exist
}

Also if that wasnt enough, you can also check using

if (typeof $.fn.myPlugin === 'function') {
    // The plugin exists
} else {
    // The plugin does not exist
}