Question

I often see this described as the way to assure a safe environment for a jQuery plugin:

(function($){
  $.fn.myPlugin = function() {
    ...
  };
})(jQuery);

Wouldn’t it be better to also safeguard undefined, like so:

(function($, undefined){
  $.fn.myPlugin = function() {
    ...
  };
})(jQuery);

Or does it not matter? and if so, why?

Answer 1

It is probably not necessary. If you test whether a variable is undefined, you should prefer using

typeof variable === 'undefined'

anyway.

“Safeguarding” jQuery on the other hand is something you definitely should do, otherwise your plugin will not work if jQuery is used in noConflict mode.